Demonstrations

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.









Sink & Float Rocks………………… ………Density

Scratch & Sniff Minerals……………………Smell

Mineral Taste Test…………………………..Taste

Very Attractive Minerals……………………Magnetism

An Acidic Reaction………………………… Carbonate Acid Test

It’s Useless to be a Resistor…………………Conductivity

Tested by Fire……………………………….Flame Test

Time to Split………………………………...Cleavage

The Mineral That Gets a Suntan…………….Tenebrescence

Is it Hot in Here?…………………………….Radioactivity

I’m Seeing Double…………………………..Double Refraction

Fire From the Rock………………………….Sparks

Soft as a Baby’s Skin………………………..Hardness

Glow in the Dark Rocks…………………….Fluorescence and Phosphorescence

Light Pipes and Frosted Rocks……………...Fiber Optics

Wild and Cool Colors……………………….Iridescence, Schiller, and Pleochroism

How to Bend a Rock………………………...Elasticity

Can You Find the Real Diamond?…………..Refraction and Dispersion

The Popcorn Mineral………………………..Expandability

Notes on Sources of Minerals and Equipment

Notes on Demonstration Techniques

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Sink & Float Rocks



Object: Students experience the density of rocks

and minerals first-hand.

Procedure description: Students heft samples of

pumice and scoria and guess if they are heavier

or lighter than water. Then they simply drop

the specimens into a tank of water to test if

they will float.



Specimens to test: Pumice, scoria (lava rock), obsidian,

quartz, galena.



Equipment needed

A large, transparent, plastic tank or bucket half-full of

water (the shape doesn’t matter, but size depends in how

big your biggest piece of pumice is), a towel or a two-

foot by two-foot carpet, and a pair of tongs (salad tongs

will work). It is important to get a plastic tank or bucket

rather than a glass one: a glass tank will only last as long

as it takes for a student to drop a big chunk of obsidian

or galena into it, cracking its bottom. A clear plastic jar

such as those used to sell pretzel rods will work well. The

tongs are good for fishing out samples from the tank and

the carpet or towel helps keep wet rocks from dripping

water everywhere.



Scientific discussion

Pumice is a volcanic rock. It forms because it has a considerable amount of gas whipped into it

while it is still molten. Upon hardening, the gas bubbles become millions of tiny pockets, filled

with air. If a specimen has enough of the pockets such that its bulk density is less than that of

water, it will float. Most chunks of pumice will float but some specimens will sink. Try to find

some samples that will sink along with a bunch that float – “sinkers” are always fun because they

will fool most students. Pumice, sold as “pumice stone,” is used to scrub calluses off the bottom

of your feet. If you can’t find pumice elsewhere, try looking in a health and beauty supply store

for “pumice stone.”

Sink & Float Rocks Page 2 of 2



Scoria is a volcanic rock similar to pumice, but it tends not to have as many gas pockets as pumice.

Having fewer air pockets, scoria is denser and, even though it looks similar to pumice, most scoria

samples will sink in water. Scoria is the “lava rock” used in gas barbeque grills and it is also used

as a decorative ground cover in gardening (often colored dark red). You can buy samples of scoria

as many garden supply centers. Most scoria is much denser than pumice, but try to find some

scoria chunks that will float along among those that sink.



Note that some floatable pumice or scoria can become water-logged and sink after sitting in water

too long.



Additional possibilities: With a little practice, you can sense some density differences by heft

alone. One way to test this is to select similar sized specimens of pumice, scoria, obsidian, quartz,

and galena. Pumice will be lightest, followed by scoria. Obsidian and quartz are very close in

densities. Galena, being lead sulfide, is considerably more dense that quartz. One dramatic way

to demonstrate this is to blindfold a student, then have him or her hold each specimen in turn and

try to rank it according to density.



It is also possible demonstrate density differences with a simple balance beam. Chose a piece of

galena, then find a chunk of (dry) pumice that weighs the same amount (if necessary you can trim a

heavier chunk of pumice down). Using a yardstick, attach the galena and pumice to opposite ends

of the stick. Then show that the stick will balance on its mid-point. (You can balance the stick on

the edge of your hand, or cut a triangular shaped block of wood to act as the fulcrum.) The pumice,

of course, will be visibly much larger than an equivalent weight of galena.



Sinking wood makes an interesting addition to a sink & float demonstration. Some wood is slightly

denser than water and thus will sink. You can get pieces of ironwood, for example, from science

supply houses, that will sink readily. I purchased one package of six pieces – five of them sank

and one floated in cold water. Another source of sinking wood is your local pet shop. Among the

aquarium supplies you may find sinking wood (sometimes called Mopani wood) of various colors

that is intended for aquarium decoration, but it will work well in your sink & float demo.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show) you may want to put your sink & float specimens in sealed containers. Place

a piece or two of pumice and scoria in a cleaned, clear plastic pretzel or peanut butter jar along with

some water, then seal it up. You can demonstrate sinking and floating by simply turning the jar

upside down allowing visitors to see which pieces settle to the bottom and which float. “Minerals

that do things…”

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Scratch & Sniff Minerals



Object: Students will experience minerals and

rocks via their sense of smell. Smell

tells you that something important is

happening when you scratch a rock or

mineral. Smelly minerals can indicate the

presence of tiny invisible fluid inclusions

in minerals and rocks and give clues to

their compositions.



Procedure description: Students scratch minerals

or rocks with nail or metal file or knock

them together, then sniff them. While

many rocks and minerals will give off

some odors when scratched, fetid barite

is called “fetid” precisely because it

smells really bad – with a very strong

odor of rotten eggs.

Most students will react strongly to the smell of

some of mineral or rock samples. (Note that in

order to get a strong smell it may be necessary to

chip a fresh surface on specimens that have already

been heavily scratched by previous students.) Compare the smell of the pyrite and the fetid barite

with that of the sulfur; how does the petroliferous limestone compare? Can you tell them apart?



Specimens to test: “Fetid” barite (available from various locations including Frystown, in Berks

County, Pennsylvania – the local Amish call them “stink stones”); sulfur chunks; pyrite; marcasite;

petroliferous limestone; arsenopyrite; white quartz pebbles; Herkimer “diamonds” (quartz from

Herkimer, NY).



Equipment needed: Large nails or a coarse metal files. A short file works well – you can take old

worn-down metal files and break them into 4- to 6-inch pieces.



Scientific discussion: Scratching fetid barite breaks open microscopic fluid inclusions caught up in

the crystal when the crystal was forming. Breaking open these tiny pockets of fluid releases some

very minor amounts of hydrogen sulfide (H2S) – a gas to which your nose is very sensitive (you

can detect it at the parts per billion level).

Scratch & Sniff Minerals Page 2 of 3



Fluid inclusions in minerals are typically microscopic – smaller than 0.01 mm across – and there

may be billions of inclusions in a crystal that is only a few centimeters across. Fluid inclusions

are really small preserved samples of the fluid from which the crystal precipitated when it was

forming.

Scientists study fluid inclusions in minerals such as quartz, calcite, barite, sphalerite, and other

minerals. Fluid inclusion studies are one way to study how minerals form. For instance, they

allow us to determine the temperature of formation. Most of the fluid in a fluid inclusion is just

salt water, but gases such as carbon dioxide and hydrogen sulfide may also be trapped.



Pyrite and petroliferous limestones have similar odors. Pure sulfur smells slightly different. Some

students will describe the odor as that of “rotten eggs,” “sulfur,” “garlic,” or “natural gas,” or

describe the smell as similar to that of the hot springs at Yellowstone. Native sulfur is just pure

sulfur (S); rotten eggs give off hydrogen sulfide (H2S). Methane (CH4 – the major component of

natural gas) is naturally odorless, but we mix into natural gas a small amount of a very smelly

chemical called methyl mercaptan (CH3SH) so that you can smell the gas if a leak occurs. Notice

that all three compounds contain sulfur – the root of their bad smells. Petroleum (oil) can also be

trapped in fluid inclusions. Hydrogen sulfide frequently accompanies natural gas and petroleum

– hence the smell of petroliferous limestone, although you may notice an oily smell, too.



Additional possibilities: It is possible to obtain quartz crystals with large visible inclusions (with

fluids, gases, and/or solids). Herkimer “diamonds” – quartz crystals from Herkimer, NY – often

show solid black inclusions of a material called anthraxolite (which is an amorphous organic

material). Part of the sparkle of Herkimers is due to the fact that they frequently have large interior

flaws – some of these flaws are large empty fluid inclusions (small cracks can allow fluids to

escape). Some quartz crystals can also be found with large visible fluid inclusions; these inclusions

often contain gas bubbles (which may include water vapor, methane, or carbon dioxide) that can be

seen to move when you tip the crystal back and forth.



Quartz nodules called “enhydros” may also be obtained. These are essentially geodes that contain

water. By careful cutting and polishing, a lapidary can work the nodule to the point where one

side is thin enough that it is possible to see the water sloshing around inside, but the nodule still

remains sealed. Enhydros and crystals with large visible inclusions can be used to show students

that fluid-filled inclusions are real.



Marcasite – an iron sulfide mineral – like some pyrites – will smell sulfurous, especially if it is

falling apart. (We call the tendency of pyrite, marcasite, and other sulfide minerals to decompose

and crumble “pyrite disease.”) Other sulfide minerals such as sphalerite or galena may also give

off a sulfurous odor when scratched. Arsenic minerals may give off an odor more like “garlic”

– the smell of arsenic.

Scratch & Sniff Minerals Page 3 of 3



By the way, I’ve also noticed that some water-rounded white quartz pebbles sold as

landscaping rocks will, when knocked together, give off a sulfurous odor. This is probably

due to a slight amount of hydrogen sulfide in their fluid inclusions, too.



One may find other smelly rocks and minerals. Clay minerals, such as kaolinite, will have

an earthy or clayey smell when damp. Experiment with other minerals and rocks – strongly-

smelling specimens are usually found associated with sedimentary rocks.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such

as at a booth at a trade show), I’ve found that fetid barite and sulfur work best. It is simplest

to have the test specimens in pairs. Ask your visitors to rub two pieces of fetid barite

together, and then take a big whiff.



One should note that different people have sharper or duller senses of smell. Thus, most

people will react strongly to fetid barite while some others will barely smell it. Kids often

have keen senses of smell. Older adults, on the other hand, may have lost much of their

sense of smell.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Mineral Taste Test



Object: Students will experience minerals and rocks

via their sense of taste. Some common

minerals dissolve quickly and have a

distinctive taste; others don’t dissolve, but

have a characteristic textures when tasted.



Procedure description: Small samples of the various

specimens are placed in individually

labeled containers (small zip-locks or

film canisters) so that students can taste

test them. Students taste the samples and

compare the tastes – they get to keep the

samples. The best way to taste-test water-

soluble minerals is wet your finger, rub your

damp fingertip on the mineral, and then rub

your finger along the edge of your tongue.

This limits the amount of mineral ingested.

Braver students will lick the samples with

the tips of the tongues. When testing for

texture, however, it is necessary to actually

put a small amount of the mineral or rock

in your mouth.

Specimens to test: Calcite or quartz crystals; granular halite; hanksite; epsomite or Epsom salts;

rock candy; bentonite; kaolinite; pyrite.



Equipment needed: Used film canisters (you can get them for free from most camera shops) or

small individual seal/lock plastics bags. Break up a small amount of each mineral or rock and

place the chips in properly-marked containers.



Scientific discussion: Halite, also called rock salt (sodium chloride – NaCl), has a salty taste – this

is where we get our table salt. Hanksite is a sodium potassium sulfate carbonate chloride mineral,

Na22K(SO4) 9(CO3) 2Cl, and also has a salty taste.



The mineral epsomite and man-made Epsom salts are chemically identical: they are both hydrated

magnesium sulfate, MgSO4·7H2O. A related mineral, hexahydrite, is also a hydrated magnesium

sulfate mineral, MgSO4·6H2O. It is easier to find Epsom salts (in most grocery stores) than the

mineral epsomite. All of these have the same bitter taste.

Mineral Taste Test Page 2 of 2



Quartz and calcite, if well cleaned, should have no taste. They are useful as blanks. Cleaning

specimens well and rinsing them well is important. Students may report that many specimens may

taste salty because salt in the sweat in their hands gets onto the specimens. I even heard of one

episode wherein a geology student was reporting that each specimen he examined tasted salty – it

turned out that the student in line before him had been using some 10% hydrochloric acid to test

each mineral for reactivity, hence the salty taste!



Of course, one cannot wash halite, hanksite, or rock candy, because they are very soluble in water.

They will even dissolve in just the sweat on your fingers. If you touch halite, then taste-test calcite,

you’ll probably transfer salt from the halite to the calcite.



Pyrite sometimes has a “sulfurous” taste – this is really a smell. Much of what we call a taste is

really a smell.



Some specimens have a characteristic texture. Most rocks or minerals will be gritty when crushed

up and tasted. Bentonite is a clay, generated from alteration of volcanic ash. It is composed of

smectite clay minerals, mainly montmorillonite. It has the interesting property of having a smooth

or creamy texture (rather than being gritty) when placed in the mouth. We take advantage of this

creamy texture when we use it in non-dairy coffee creamers (yes, you really are putting a rock in

your coffee!).



Other minerals have a characteristic tendency to stick to your tongue when tasted. Magnesite,

kaolinite, montmorillonite, and chrysocolla fall in this group. When dry, these minerals absorb

water and stick to your moist tongue.



Additional possibilities: Being man-made, rock candy is not a mineral even though it looks like

one. Still including it in this taste test is a good treat especially if you give it to the students after

they have already tasted salty and bitter minerals. You can purchase rock candy (really just sugar

crystals) on small wooden sticks – sometimes it has been dyed or flavored as well. Rock candy

that is precipitated from maple sap will have a maple flavor.



Other minerals can also be taste-tested: Borax has a sweet alkaline taste. Ulexite is alkaline. Sylvite

is bitter. Glauberite is described as being bitter and salty. Melanterite has a sweet, astringent,

metallic taste. Chalcanthite has a sweet metallic taste and is slightly poisonous.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), I’ve found that it is simplest to use only halite. When demonstrating taste

for a group, I have each person hold out his or her hands palms-up, and then use a small hammer (a

metal meat-tenderizing mallet works well) to knock small chips of the rock salt onto their palms.

They can then taste the chips using their fingers or their tongues.



Special Note: Do not use other minerals or materials for this demo unless you are sure that they

are safe.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Very Attractive Minerals



Object: Students will determine that some

minerals, rocks, and other materials

are naturally magnetic.



Procedure description: Test specimens with

a magnet to see if the magnet will

stick to them. If the magnet won’t

stick, hold it lightly between your

thumb and index finger and pass it

over the specimen. Do you feel a

slight tug? Then take the specimen

and pass it slowly around a magnetic

compass that is sitting still on a firm

flat surface (a table top). Does the

specimen cause the compass’ needle

to deflect?



Specimens to test: Magnetite crystals,

lodestone, franklinite, chromite, specular

hematite, limonite, iron meteorite, stony

meteorite, refrigerator magnets, iron or steel,

copper pennies, aluminum foil.



Equipment needed: Magnets, large compass;

mini-compasses.



Scientific discussion: Strongly magnetic materials will be attracted by a magnet. You’ll be able

to feel the pull when you hold the magnet close to the specimen. A compass needle is more

sensitive to weakly magnetic materials. A mineral that is too faintly magnetic to be felt may still

be observed to deflect a compass needle.



Iron and steel will be attracted by a magnet. These metals will also deflect a compass needle,

but metals such as aluminum and copper won’t. The (rare) mineral native iron and iron found in

meteorites are strongly attracted by a magnet. (Iron meteorites are mostly nickel-iron; many stony

meteorites also have small blebs of nickel-iron scattered throughout their interiors.) Iron, steel,

and nickel-iron are magnetizable, meaning they can be made magnetic. For instance, stroking an

iron paper clip a hundred times in the same direction with a strong magnet will make the paper clip

into a magnet – the clip can then be used to pick up other paper clips.

Very Attractive Minerals Page 2 of 2



You will find that magnetite will deflect the compass needle. Some magnetite crystals are much

more strongly magnetic than others. Lodestone is massive magnetite and by definition is strongly

magnetic. Frequently, lodestone samples will be found covered with a black “fuzz.” This magnetic

fuzz consists of small chips or dust from the lodestone and/or small metal filings.



Additional possibilities: Magnetite and maghemite are strongly magnetic. Minerals that are weakly

magnetic include chromite, franklinite, ferberite, siderite, tantalite, babingtonite, and ilmenite.

Pyrrhotite specimens are erratic: some are strongly magnetic others are weak. Some specimens

of hematite may be magnetic, too. This may be because they are really mislabeled magnetite, or

it could be because small amounts of magnetite are intermixed with the hematite. Limonite may

form from weathered magnetite and a residue of unaltered magnetite may render some limonite

specimens magnetic.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at

a booth at a trade show), I’ve found that it is simplest to use only lodestone, one or two magnets,

and a compass.



Another way to demonstrate magnetism is to make a “compass-board.” Obtain at least four to as

many as twelve mini-compasses (they can be purchased from Edmund Scientific or other science

supply houses). Glue compasses in a circle (about 3-4 inches in diameter) around a spot on a flat

board. Put specimens in center – watch for movement of compasses. If the specimen is strongly

magnetic, note how the north ends of some compasses point toward the specimen while others

point away. Move the specimen around the circle of compasses and watch how they swing back

and forth.



Iron filings can be used to show the pattern of the magnetic field around a lodestone. One way

to keep the iron filings from escaping and contaminating everything is to build a magnetic field

viewer. Take two clear pieces of clear, rigid Plexiglas, each cut to about 6 inches square. Lay one

piece flat on a table and run a bead of silicone cement around just inside the edge of the piece.

Distribute several small scoops worth of iron filings or magnetite dust in the center. Then place

the other piece of Plexiglas on top and push down so that the silicone cement contacts both sheets

and traps the magnetic iron filing inside the resulting “sandwich.” Try not to get the filings into

the cement – do not move the magnetic field viewer until the cement has set. Once the cement has

set, the finished magnetic field viewer can be used. Set a magnet or a piece of lodestone on top of

the center of the Plexiglas sheets. Observe how the iron filings arrange themselves parallel to the

lines of the invisible magnetic field surrounding the lodestone. Note that the lodestone has two

magnetic poles.

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







An Acidic Reaction



Object: Students will use a chemical

reaction to test for the

presence of carbonate in

calcite and limestone. By

dropping a small amount of

an acid on these specimens,

they will observe bubbles of

carbon dioxide forming from

the reaction of the acid with

carbonate minerals.



Procedure description: Students

test specimens by dropping

one or two drops of 10%

hydrochloric acid on them.

Production of bubbles of carbon dioxide indicates that the carbonate ion is present. After testing a

specimen, use a water-filled squirt bottle to wash off the acid into a basin. (The acid waste in the

basin can be treated with baking soda to neutralize it and then disposed of by washing it down a

drain.)



Specimens to test

Calcite; limestone; dolomite; dolostone; sandstone; orthoquartzite; strontianite.



Equipment needed

Small plastic dropper bottles containing 10% hydrochloric acid solution; safety glasses or goggles;

squirt bottle with water; basin.



Scientific discussion: Upon reaction with 10% hydrochloric acid, carbonate minerals and carbonate-

bearing rocks will react to release carbon dioxide gas. The gas appears as bubbles in the solution.

This effervescence is often used by geologists to test rocks for the presence of carbonate minerals

such as calcite or dolomite.



Calcite reacts strongly with the acid. Limestone, which is mainly composed of calcite (calcium

carbonate), will also react strongly. Limestones may contain impurities, however, and less-pure

limestones will react less vigorously.



Dolomite is a mineral (calcium magnesium carbonate) that is related to calcite and is likewise

often found in sedimentary rocks. Dolostone is the rock that is composed mainly of the mineral

dolomite. The term “dolomite” is also used to refer to dolostone rock.

An Acidic Reaction Page 2 of 2

Dolomite/dolostone reacts with acid much less vigorously than limestone; often it is necessary to

scratch up the surface of the dolostone to produce a powder that will then be observed to react with

the acid. Geologists use this behavioral difference as a field test to discriminate between limestone

and dolostone.



Sandstones are composed of grains of quartz sand. Some sandstones (sometimes called

orthoquartzites) are cemented together with quartz cement while others will have a calcite cement.

The calcite cement will react with hydrochloric acid and those sandstones with calcite cement will

display effervescence.

Additional possibilities: It is possible to use other carbonate minerals and produce the characteristic

bubbles. Strontianite (strontium carbonate) is another mineral that reacts vigorously with 10%

hydrochloric acid.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at

a booth at a trade show), I’ve found that it is simplest to use calcite and limestone. I do the demo

myself – don’t want a lot of people handling the acid – in a small basin with a few chips of calcite

and a piece of limestone. First, I show the reaction with calcite, next I demonstrate that the same

reaction occurs in the limestone. Then, I put away the dropper bottle so kids can’t get their hands

on it. It is important to stress to visitors that this experiment shows that limestone can be used

to neutralize acid – it serves in this role when we use it to treat acid rock drainage and to scrub

sulfuric acid from power plant stack gases.



Special note: Use of acid by youngsters should be supervised. Goggles or safety glasses are required

and lab coats or aprons may be useful. A 10% solution of hydrochloric acid is not particularly

dangerous, but it will irritate the skin and harm your eyes. Promptly wash off any acid on skin or

clothes. Baking soda serves as a useful neutralizing agent for spills and waste.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







It’s Useless to be a Resistor



Object: Students will observe that some minerals are natural electrical conductors while others

are good insulators. They use a simple electrical circuit to test whether a sample is

conductive.









Procedure description: Students bring both of the leads of a conductivity tester into contact with

a specimen to test if it will pass electricity.



Specimens to test: Native copper; native silver; native gold; graphite; molybdenite; mica; quartz;

pyrite; pyrrhotite; magnetite; specular hematite; galena; chalcopyrite; pennies;

copper wire; pencils.



Equipment needed: A conductivity or continuity tester – these can be purchased at hardware stores

and science supply houses. (Elenco makes an inexpensive lab meter kit – available from American

Science & Surplus for $4.95, cat # 37977, call 888-724-7587 for a catalog.)



You can make you own conductivity tester with a simple battery-powered circuit. Use lightweight

electrical wire and strip the ends to serve as probes. Connect one wire to one terminal of a battery

pack, and connect the other wire to a small flashlight light bulb. Then wire the other terminal of

the battery pack to the alternative connection point for the light bulb.

It’s Useless to be a Resistor Page 2 of 2

Test your work by crossing the stripped ends of the wire – the bulb should light up. Alternatively,

you can wire a buzzer in place of the light bulb. The bulb will light or the buzzer will sound if you

touch both stripped ends (the “probes”) firmly to a specimen that is an electrical conductor. This

apparatus is only sensitive to good conductors.



Scientific discussion: Minerals that are native metals are natural conductors. Thus, native gold,

copper, and silver (as well as rarer minerals such as native lead) are good conductors of electricity.

These minerals look like we expect conductors to look. It is important to realize that even a

minor amount of tarnish or oxide coating on native silver or native copper can interrupt electrical

continuity. Experimenters should also be aware that some native copper specimens are sold after

they have been coated with a clear layer of varnish (to protect them from tarnishing). A coating of

varnish will interrupt electrical continuity.



Graphite is a good conductor even though it doesn’t look like the metals. Large chunk graphite can

be obtained from Madagascar. Graphite is rather common in metamorphic rocks such as marble.

One interesting way of demonstrating that graphite is a conductor is to sharpen both ends of a No.

2 pencil. Touch the conductivity tester’s probes to opposite ends of the doubly-sharpened pencil;

the pencil “lead” will pass electricity. Pencil “lead” is, of course, really graphite – but a certain

amount of clay may also be mixed in during its production. The addition of clay causes the pencil

lead to be a poorer conductor than pure graphite, but all of the pencils I tested still passed enough

electricity to register on my conductivity tester.



You can have students test the conductivity of sulfide minerals such as pyrite, pyrrhotite, chalcopyrite,

or galena that have metallic luster. Molybdenite (molybdenum disulfide) is similar to graphite in

appearance (it is blue-gray rather than just gray). Including examples of known conductors such

as copper pennies and electrical wires is useful. Sulfide minerals are poorer conductors than the

native metals and a small amount of surface oxidation will significantly lower their conductivity.

Test freshly broken surfaces where possible. The response you get with your conductivity tester

will also depend upon the voltage of its circuit.



Not everything that looks shiny is a conductor. Muscovite mica, even though it has a bright silvery

look, is an excellent insulator. Quartz is another insulator.



Additional possibilities: Iron meteorites are good conductors of electricity as long as any rust

coatings have been removed. A polished slab of an iron meteorite, or a mesosiderite, make a

fascinating addition to the conductivity demo. Magnetite and specular hematite are also interesting

to test.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), I’ve found that attaching the conductivity tester and gluing the minerals to

be tested to a single wooden board is a good way to keep all of the various parts together. If you

put out a native gold sample to test, you don’t want it to disappear.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Tested by Fire



Object: Everyone loves fireworks and

students often wonder how

fireworks get their rich colors.

Using the flame test, students can

produce their own colored flames

and learn about fireworks, minerals,

and their common elements.



Procedure description: Students use a

hammer and chisel to break small

chips off specimens. Chips are

crushed with a mortar and pestle

and the dust placed in a Petri dish.

A few drops of 10% hydrochloric

acid are dropped on the dust and

stirred around.

A platinum wire loop is dipped in the mixture; a small amount of solution adheres to it. Placing

the loop in the flame, students see a colored flame for a few seconds. Some elements give

characteristically unique colors in the flame and thus the flame test yields clues to the elements

making up a tested specimen. Clean the loop between tests to avoid cross-contamination (clean

the loop by dipping it in clean acid and then heating it in the flame, repeating until no more colors

are generated by the loop).



Specimens to test

Malachite; strontianite; celestine; calcite; barite; halite; sylvite or salt substitute (KCl type).



Equipment needed: Safety glasses or goggles; hammer; chisel; 10% hydrochloric acid in small

dropper bottle; mortar and pestle (or use a steel plate and small hammer); Petri dishes or small

plastic cups; platinum wire loops mounted on glass rods (or long tweezers – a separate pair for

each mineral tested); source of flame (Bunsen burner attached to gas jet, an alcohol lamp with

alcohol, or a propane torch attached to a gas cylinder); fire extinguisher.



Scientific discussion: Metal cations, dissolved and then ionized in a hot flame, will give off light

that is characteristic of the element. The actual color we see is from the combination of a number

of discreet bands of colored light; these bands are created by the energy states available to the

element’s electrons. You can’t see the separate bands without a spectroscope, but observing the

color a mineral produces in a flame with the naked eye still gives clues to the elements in the

mineral.

Tested by Fire Page 2 of 3

Strontianite (strontium carbonate) gives a very rich crimson color in the flame, the same crimson

color seen in red fireworks. This flame test never fails to impress students.

Barite (barium sulfate) gives a yellowish-green flame.

Calcite (calcium carbonate) yields a yellowish-red flame, often described as a “brick red” as

opposed to the crimson of a strontium flame.

Copper can give a green or blue flame dependent upon the cation. In the Cu(II) state (Cu ) copper

+2





gives a strong green flame; in the Cu(I) state (Cu ), it gives a blue flame.

+1





Malachite is copper(II) carbonate hydroxide with the copper in the +2 state. Thus, it gives

a green flame, although in practice you will sometimes see splotches of blue flames as

well, especially when using hydrochloric acid to dissolve the malachite.



Sodium gives a very strong yellow color that overwhelms other colors.

Testing for potassium is difficult because the lilac color of potassium’s flame can’t be seen in the

presence of sodium. The mineral sylvite (potassium chloride) should give a lilac purple

flame but contamination from sodium is difficult to avoid.

Try testing “salt substitutes” sold in the grocery store to see if these are really sodium-free; most

of these salt substitutes are potassium chloride (sylvite) rather than “salt” (i.e., halite,

or sodium chloride). Sodium is a very common element as it is often difficult to keep

samples (and tools) completely free of salt contamination. (There may even be sodium

contaminating your 10% hydrochloric acid solution if care was not taken when it was

made up.)



Additional possibilities: You may be asked by a student how you know that the metal cation is

causing the flame color and not the other ions in the mineral. This is a good question. One way

to answer the question is to demonstrate that two different minerals can give the same flame

coloration. For instance, if you do a flame test on strontianite (which is a white mineral with an

acicular habit) you get a crimson flame. Strontianite is strontium carbonate, SrCO . If you test

3



celestine (typically a light-blue mineral with more tabular crystals) you will likewise generate a

crimson flame. Celestine is strontium sulfate, SrSO ; strontium is common to both minerals. (An

4



observant student will note that oxygen is common to both minerals, too, but a moment’s thought

will lead one to ask why, if oxygen causes the crimson color, the flame isn’t always crimson? After

all, the flame burns oxygen from the atmosphere continuously.)



If you don’t have a mortar and pestle or a platinum loop tester, alternatives exist. You can use

a hammer and a piece of metal to powder small amounts of softer minerals (such as those listed

here). An alternative to the platinum loop is to use long-handled tweezers. In this case, don’t

powder the mineral, just break it into small chips. Then use the point of the tweezers to pick up a

small chip, dip it in a drop of acid, and then stick it into the flame. This doesn’t work as well as the

platinum loop. The acid and the flame’s heat will corrode the metal of the tweezers, but you can

use them for a number of tests if you clean them promptly. I dedicate a separate pair of tweezers

to each mineral being tested to avoid cross-contamination problems.

Tested by Fire Page 3 of 3



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), I’ve found that it is simplest to use a propane torch with a quick-start valve

and piezoelectric igniter. This allows me to ignite the flame only when I’m immediately ready to

do the flame test. I don’t have to leave the flame on, continuously generating fumes and risking an

accident. Using the short and stout propane cylinders rather than the long and skinny ones gives

the torch more stability, too.



I also pre-crush some malachite and strontianite and store the powders in used plastic film canisters.

Pour out a little of the powder, wet it with a few drops of acid, stir it with the platinum loop, then

let a visitor insert the loop into the flame. They hold the loop but you control the flame for safety’s

sake.



Special notes: It is always a good idea to have a fire extinguisher handy when working with flames.

Used and unwanted acid can be neutralized with baking soda and washed down a drain.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Time to Split



Object: Students will break minerals

and observe their cleavage

or fracture. How a mineral

breaks depends upon the

mineral’s structure. Cleavage

is an easily demonstrated

property of minerals such as

calcite, halite, and mica.



Procedure description: Students,

wearing safety goggles, place a

specimen on a block of wood.

Then, using a small hammer

and a cleaving chisel, they

break the specimen to show its

cleavage or fracture.



Specimens to test: Calcite; muscovite

mica; halite; chert; flint; quartz.



Equipment needed: Safety glasses or goggles; small hammer (full-size hammers give too much

power to an ambitious youngster – I favor using a small aluminum meat tenderizer with the

faces ground flat – it is lighter than a steel hammer); wood block to use as a chopping block; and

a cleaving chisel. Cleaving chisels are hard to find but you can easily make your own. Take

a cheap one-inch-wide wood chisel and dull the sharp end with a grinding wheel. Then use a

grinder to sharpen a knife-edge along one side of the chisel. You use the cleaving chisel by

placing its sharpened side edge against a crystal (it is best to try to align the chisel in the direction

of an existing cleavage surface) and then firmly striking the other side of the chisel.



Scientific discussion: Cleavage is related to the underlying structure of the mineral. In the case

of mica, the mineral consists of planar sheets of atoms with relatively weak bonds between the

sheets. This enables us to easily split micas into very thin sheets. We call this perfect basal

cleavage. You don’t need a chisel to cleave mica – you can use your fingernail or a knife blade.

It’s possible to peel off sheets of mica that are thinner than a piece of paper. Thin sheets of mica

are transparent enough to see through.

Time to Split Page 2 of 2



Halite has three directions of perfect cleavage each perpendicular to the others. Cleavage fragments

tend to be cubes or rectangles with right-angle corners reflecting the underlying isometric (cubic)

atomic structure.



Calcite has three directions of cleavage that are inclined to each other. A calcite cleavage fragment

will take the shape of a rhombohedron.



Additional possibilities: It is possible to demonstrate four different directions of perfect cleavage

in fluorite. One can cleave fluorite into an octahedron by knocking off the corners of a cubic

crystal. Fluorite is frequently sold in the form of single octahedra – these are cleavage fragments,

not complete crystals. Good cleavable fluorite is more expensive than calcite, so you may just

wish to have one or two cleavage octahedra to show students.



Quartz and flint or chert will show conchoidal fracture – they break with a shell-like pattern on

the fracture surface. Quartz, flint, and chert, will not exhibit any flat cleavage surfaces. You can

demonstrate conchoidal fracture in quartz but you have to be careful – fragments will have very

sharp edges.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at

a booth at a trade show), I’ve found that it is simplest to use small cleavage fragments of calcite

– they will lay flat on the chopping block and it’s easy to see how to align the cleaving chisel

parallel to a cleavage plane. Be sure to select clean calcite for cleavage demos – it doesn’t have

to be optical grade – but it should be untwinned. Block crystalline halite (not the coarse granular

halite) works even better than calcite, but it is a little bit harder to obtain in quantity.



I have youngsters put on safety glasses before trying their hand at cleaving calcite or halite and

allow them to keep samples of the cleavage fragments they produce.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







The Mineral That Gets a Suntan



Object: Exposure to ultraviolet light causes changes in minerals. One of the lesser-known

phenomena is tenebrescence, in which a mineral actually changes color upon exposure to

ultraviolet light (this is not the same as fluorescence). Using an ultraviolet light, students can give

a mineral a reversible “suntan.” They’ll change the color of hackmanite or tugtupite, then allow

the specimens to change back to their original color.



Procedure description: After noting the specimen’s original color, students hold a UV lamp close to

a specimen of hackmanite or tugtupite and observe the changing color. Hackmanite, for instance,

changes from white to purple-red. After a few minutes, pull the UV lamp away from the specimen.

Note the purple-red color. When the specimen is subsequently exposed to white light (such as that

coming from a fluorescent light), it will quickly “relax” back to its original color. This cycle can

be repeated again and again. Test other photochromic materials such as an old pair of PhotoGray®

glasses, some “UV beads”, or photochromic fingernail polishes in a similar manner.



Specimens to test: Hackmanite (a variety of sodalite, the best material comes from Ilimaussaq,

Greenland, although good Canadian material is also available); tugtupite; an old pair of PhotoGray®

glasses; “UV beads”; photochromic fingernail polish.



Equipment needed: Ultraviolet lamp (short-wave UV is best for these demos); small piece of thick

glass.



Scientific discussion: When some minerals such as hackmanite are exposed to ultraviolet light

(short-wave UV is best) they change from white to a purple-red or raspberry color. Called

tenebrescence, this effect is also known as reversible photochromism. “Tenebrae” is Latin for

shadow or darkness – in this case the mineral acquires a purple shadow. The effect is reversible

in hackmanite: under white light the raspberry color fades back to white. (Technically, this effect

in sodalite, variety hackmanite, appears to be due to substitution of sulfur for chlorine in the

structure, but there is usually not much need to go into such details during demonstrations.) The

mineral tugtupite has similar abilities.



Tenebrescence is a rare phenomenon in nature – only hackmanite and tugtupite show the effect

readily. Light-colored spodumene is also tenebrescent and will turn green. However, it takes

X-rays or higher energy radiation to achieve the green color. This green color will fade upon

exposure to light or heat.



We use synthetic materials with tenebrescent characteristics. For instance, glass PhotoGray®

lenses have small silver halide crystals imbedded in them that react to ultraviolet light to darken

the lenses. These PhotoGray® glasses and other similar eyeglass lenses only darken in the outdoor

The Mineral That Gets a Suntan Page 2 of 2



sunlight because it takes ultraviolet light to set off the tenebrescent effect. Indoor lamps produce

very little UV light, and sunlight shining through a window has little UV light because the window

glass absorbs most of the ultraviolet, so the glasses don’t darken indoors. You can also see the

tenebrescence in “UV beads” and photochromic fingernail polishes.



Additional possibilities: Show students that glass will adsorb ultraviolet light by placing a piece

of thick glass between the UV lamp and a specimen. Most glass will not allow UV light to pass

through, thus the specimen, when protected by the glass, will not show the tenebrescent effect.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at

a booth at a trade show), I’ve found that it is best to use one of the strong high-output UV lamps

manufactured by companies such as Way Too Cool, Inc., or UV Systems, Inc. (See the web

page of the Fluorescent Mineral Society www.uvminerals.org for dealers that sell these and other

lamps.) These lamps are available with long-wave and short-wave UV bulbs. Although they are

expensive, these lamps can be used for a wide variety of demonstrations and they will give good

results with tenebrescent hackmanite, or tugtupite.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Is it Hot in Here?



Object: Radioactivity is more common

than you suspect. Students

can detect radioactive rocks

and minerals with a Geiger

counter and investigate

the radioactivity of some

household items.



Procedure description: Students

test rocks, minerals, and

some household objects for

radioactivity using a Geiger

counter. Hold the Geiger

counter’s probe near the

specimen to be tested.

Some radiation monitors have special

windows and/or covers that allow you to discriminate between alpha-, beta-, and gamma-

radiation.



Specimens to test: Uranium minerals such as carnotite; thorium minerals; petrified wood (pieces

from the Colorado Plateau may be radioactive); thorium mantles for Coleman gas lanterns;

smoke detectors; radium dial alarm clocks and wristwatches; antique Fiesta Ware.



Equipment needed: A Geiger counter; other types of radiation detectors could also be used.



Scientific discussion: Naturally occurring radioactive minerals and rocks will give off alpha

particles, beta particles, and/or gamma rays.



You do not need any special permits to handle naturally radioactive materials, but care in their

handling is prudent. Limit your exposure time and avoid dust from radioactive minerals. You

might want to store them in your garage or other well-ventilated space (to limit build up of radon

gas).



Many mineral dealers will have at least some uranium minerals for sale. Carnotite, autunite, and

tobernite are the more common radioactive minerals sold – it is also possible to find petrified

wood and dinosaur bones that are radioactive.

Is it Hot in Here? page 2 of 2



Thorium mantles can be purchased in sporting goods stores. Old smoke detectors can be opened to

expose the sensor. Note that the back of the smoke detector will have a notice reading something

like “Contains radioactive material: 0.9 microcuries of americium-241.” A button of americium-

241 is in a metal can inside the smoke detector and, because it is an alpha-emitter, it is very hard

to detect without cutting the can open. However, visitors are usually impressed when they read

the notice on the back.



Additional possibilities: It is possible to acquire radioactive items such as radium dial alarm clocks

and wristwatches in junk shops. These clocks will have dabs of pale green paint on the clock hands

and at the numbers. This paint is a mixture of a phosphor and a small amount of radium. The dials

no longer glow in the dark because the phosphor is burnt out. But the radium is still present and

radioactive.



From before World War II until 1973, the Fiesta Red style of Fiesta Ware dinnerware was made

with a bright orange uranium-rich glaze. You can still find radioactive Fiesta Ware cups, plates, and

bowls in antique shops. Note: not all Fiesta Ware is radioactive, and not all radioactive dinnerware

is Fiesta Ware. Also, antique ceramic dinnerware with glaze colors other than bright orange may

also be radioactive – it is best to actually test pieces before buying one for demo purposes. Radium

dial clocks and Fiesta Ware are nicely radioactive (without being overly dangerous for casual use)

and will give a strong response on a Geiger counter. They are an interesting piece of history and

instructive to students.



It is also instructive to show how radioactive shielding works. Place a thin piece of metal between

a radioactive mineral and the Geiger counter will shield out the alpha-particles and most of the

beta-particles but will not truncate gamma-rays. Likewise, alpha particles will not pass through

your skin, so if you put your hand between the specimen and a uranium mineral you will see a

substantial decline in the count rate. If you can get hold of a lead brick you can use it for shielding

demonstrations, too.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as

at a booth at a trade show), I’ve found that it is a good idea to place any radioactive minerals or

rocks inside clear plastic bags. This keeps radioactive dust from contaminating other samples

you are showing. This is important because most of your specimens will be relatively low-level,

and the radioactive dust, while not enough to be hazardous to health, will get on non-radioactive

specimens and only serve to confuse students.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







I’m Seeing Double



Object: Double refraction is easily

observable in optically-clear

calcite. Students observe

double refraction and prove that

calcite not only refracts light to

produce two images, but that

light passing through calcite is

also polarized.



Procedure description: Students draw a

line across and write several

letters or symbols (“+”, “#”,

and “$”work well) on a white

sheet of paper.

They take a cleavage fragment of optically-clear calcite; place it on the sheet, over a symbol.

Observe how the marks look through the calcite. How many images do you see? What happens

when you rotate the calcite sitting over the mark? Then they hold a sheet of Polaroid polarizing

material between the calcite and their eye. How many images do you see now? What happens

when you rotate the calcite sitting over a mark while looking through the Polaroid polarizing

sheet?



Specimens to test: Calcite, optical-grade (“Iceland spar”) cleavage fragments are necessary, the

bigger the better. As control, you can use another clear mineral such as quartz.

Equipment needed: Polaroid polarizing sheet (Edmund Scientific sells polarizing demo discs, cat#

D30386-05; call 800-728-6999); paper; pen.



Scientific discussion: Double refraction is easily observable in optically-clear calcite. Students

observe that the calcite breaks an image viewed through the calcite into two images: this is double

refraction or birefringence. Polarization of the images can be proven by placing a polarizing screen

over the calcite. You can rotate the polarizing screen to a position where one of the two images

disappears. This happens because the polarizing screen eliminates light that is polarized in one

direction while passing light polarized at right angles to that direction. When the polarizing screen

is aligned correctly it will eliminate completely the light that carries one of the images. Rotating it

will eliminate the other image; intermediate positions will partially weaken the images.

I’m Seeing Double Page 2 of 2





Additional possibilities: It is theoretically possible to observe double refraction in rutile if you

can get an optically clear crystal (difficult except in very small natural specimens). Synthetic

rutile, sometimes called Titania, can be a very clear light yellow and can be used. Synthetic

colorless silicon carbide (moissanite) is sold as a diamond simulant and exhibits double refraction

(unlike true diamonds). Usually moissanite gemstones are cut so that the double refraction is only

apparent when looking at them from the side.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), I’ve found that double refraction is a simple but impressive demo. Obtain

as large of pieces of optically-clear calcite as possible (nice Mexican cleavage fragments that are

three inches across can be purchased). Just place the calcite on a sheet of white paper on which

you’ve made some black marks (letters, lines, etc.) – crisp clear edges are important for maximum

effect. Note that calcite is a soft material and will scratch easily. Try to keep dust and sand away

from the faces of calcite. If a calcite fragment does get badly scratched you can always, with care,

cleave a fresh face.



If you are going to include a polarizing sheet in the demo, try clamping it to an upright stand to

keep it in place over your marked paper. Then allow the visitor to rotate the calcite between the

two. Polarizing screens will also scratch and you want to limit contact.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Fire From the Rock



Object: Early settlers used flint and steel

to start fires. Students can relive

the days of the early pioneers

when they strike sparks from

flint to make a fire.



Procedure description: Students hold

a fist-sized fragment of flint in

one hand and a piece of steel in

the other. The best technique is

hold the flint steady and strike

downward with the long edge of

the steel, hitting a crisp edge of

the flint with a glancing, grating

blow.

Hold the steel firmly between the tips of

your thumb and fingers, keeping your

knuckles clear. With practice a spray of

sparks is produced. Most sparks will fly in the direction of the blow, but it is still important to wear

safety glasses or goggles to protect your eyes.



If you catch the sparks in tinder, a flame can be created. Pioneers would have used charred cloth

and maybe mouse nests to ignite a flame, but for demonstration purposes extra fine steel wool will

serve as tinder, allowing you to nurse a spark into a flame. Hold the flint and steel a couple of

inches above a small, fluffed up patch of steel wool sitting in the center of a shallow basin. When

you strike the flint and a spark lands in the steel wool, the thin wires will begin to burn. If you blow

on the burning steel wool, it will burst into flame. With a little practice, you’ll succeed in making

fire from a rock. Use water to put out the burning steel wool and keep a fire extinguisher on hand

for emergencies.



Specimens to test: Flint; chert (higher quality material works best).



Equipment needed: Hard steel bar (metalworking files work well – break an old, used file into

pieces about three- to four-inch in length); safety glasses or goggles; extra-fine (000) steel wool;

plastic basin; water; fire extinguisher.

Fire From the Rock Page 2 of 2

Scientific discussion: Before the advent of the safety match in the mid-1800’s, flint and steel

was one of the better ways to start a fire. One advantage the flint and steel method has over

matches is that flint and steel still work after you’ve fallen in the creek.



Flint is hard enough that it knocks small chips off the steel. Small fragments of steel flying off

burning as sparks, ignited by the frictional energy of the strike. They burn hot enough that, if

brought into contact with a fuel (in the form of a fine tinder) a flame can be generated. Extra-

fine (triple-0) steel wool will burn quite readily (coarser grades will not work as well). The

steel wool’s wires are so fine that they will begin to oxidize rapidly (i.e., burn incandescently)

when hit by a hot spark. Blowing on the burning steel wool greatly increases the oxidation

rate and the steel wool can burst into flame.



Additional possibilities: It is possible to buy ready-made flint and steel fire-starting kits just

like those that the early pioneers would have carried. In these kits the steel piece is usually in

the form of a large “C”, fashioned so that you can grasp it in the manner of brass knuckles.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors be

careful with the sparks. I’ve found that many indoor venues (such as trade shows) tend to

frown on open flames so your ability to do this demo may be limited. You may have to just

show the spark-generating effect and not use the steel wool. On the other hand, burning steel

wool is very impressive: youngsters find it fascinating. You can have visitors try their hand at

the flint and steel. Occasionally, you’ll find one – usually a Boy Scout – who is really good at

it. Getting good quality flint (the best material comes from Flint Ridge, Ohio) and good hard

steel are keys to a successful demo.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Soft as a Baby’s Skin



Object: Every student encounters the Moh’s Hardness Scale in science class. The concept of

relative hardness is easily in theory but more difficult to demonstrate in practice. It is easier to

experience relative hardness at the soft end of the hardness scale.



Procedure description: Students scratch samples with their fingernails, ranking them as harder or

softer. Care must be taken to avoid mistaking a dust trail for a scratch. For instance, talc rubbed

against gypsum will leave a white trail that at first looks like a scratch. But if you wipe away the

dust, you will see that the gypsum is unmarked. Talc or soapstone has a Moh’s hardness of 1 and is

even softer than your skin. Your fingernail can scratch gypsum, which has a hardness of 2, but not

calcite, with a hardness of 3. Your fingernail thus has a hardness of about 2.5. Once the specimens

are ranked by hardness, show that softer ones cannot scratch harder ones. Thus talc cannot scratch

calcite, etc.



Specimens to test: Talc (soapstone); gypsum; serpentine; calcite; graphite.



Equipment needed: Just your fingernail and your hand.



Scientific discussion: Your fingernail has a Moh’s scale hardness of 2.5. It is harder than talc

and gypsum, but softer than calcite. Because it is possible to get good, inexpensive crystals of

gypsum and cleavage fragments of calcite with clean flat faces, it is easy for students to see if their

fingernails really can or cannot scratch these minerals.



Hardness of a solid is a function of the strength of the chemical bonds between atoms and the

arrangement of the atoms. Often it is difficult to tell if a mineral is scratching another mineral or

if it is really just powdering itself against it. The talc-gypsum-calcite sequence is relatively easy

to determine if you compare them against your fingernail.



Additional possibilities: Serpentine varies widely in hardness (about 2.5 to 5 on Moh’s scale) so

you have to test individual specimens before using them in demos. Graphite is a good addition

because it is quite soft (1.5), but it can make a mess if not kept under control.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), I’ve found that the simplest way to talk about hardness (or rather softness)

is to set out a large block of soapstone, encourage visitors to touch it, and ask them what it feels

like. Some will say “soap,” which is where soapstone gets its name, of course. Tell them to rub

their hands across the stone and look at the their hands – they’ll see a shiny white powder on their

fingers. “This mineral is so soft,” I tell them, “that it is actually softer than your skin.” I also keep

a bottle of talcum powder nearby to show them that we’re really using a mineral when we use

talcum powder.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Glow in the Dark Rocks



Object: Formerly, demonstration

of the fluorescence and

phosphorescence of minerals

under ultraviolet lamps was

possible only in a darkened

room. New, high-output

ultraviolet lamps are much

brighter than earlier lamps and

the resulting fluorescence and

phosphorescence are bright

enough, for some minerals,

to be seen even in a lighted

room. An easily made “dark-

box” still helps students

observe fluorescence and

phosphorescence in minerals

with maximum effect, however.



Procedure description: Students place minerals in the dark-box under an ultraviolet lamp and

observe the resulting fluorescent colors. If the fluorescence persists after the ultraviolet

light is turned off, the phenomenon is known as phosphorescence.

Specimens to test: Willemite and calcite from the Franklin/Sterling Hill Mines in Sussex County,

New Jersey, are strongly fluorescent (willemite – green; calcite – red) and are excellent

performers for demonstrations. These mines also produce many other fluorescent

minerals. Contact the Sterling Hill Mining Museum at (973) 209-7212 for more

details.



Other minerals from other localities that are strongly fluorescent include fluorite; opal; halite;

chalcedony; scheelite; wernerite; strontianite; calcite; and many more. For more information,

contact the Fluorescent Mineral Society (www.uvminerals.org).



Equipment needed: High-output ultraviolet lamp (short-wave is best, or get one with both long-

and short-wave bulbs); dark-box. (A dark box can be easily and cheaply made – simply get a large

sturdy cardboard box, and spray-paint the interior black. Then cut an access port on top in which

to place your UV lamp and a viewing port on the side through which you can look at specimens

placed under the UV lamp.)

Glow in the Dark Rocks Page 2 of 2



Scientific discussion: Fluorescence is the emission of light caused by the excitation of an atom’s

electrons. Unlike under simple reflection of light, when a material fluoresces, it gives off more light

of a given wavelength than it receives in that wavelength. This is possible because the material

absorbs light of a higher energy and radiates it at a lower energy. In the case of fluorescence under

ultraviolet light, the higher energy input light is the ultraviolet light, and the lower energy output

light is in the visible part of the spectrum. Thus you shine an invisible light (UV) on a mineral and

it glows with a visible light.



Phosphorescence is delayed emission of light so it continues even after the UV light is turned off.



Fluorescence may occur even under visible light alone. For instance, the “international orange”

color that hunters wear for safety is really a fluorescent orange. In this case the orange material

absorbs visible light and reemits it as orange. Thus the orange looks brighter than a merely reflective

orange. All of the “Day-Glo” colors used in paints and poster papers are fluorescent.



Additional possibilities: It is possible to demonstrate fluorescence in materials that are not

minerals. Examples include fluorescent orange safety vests, fluorescent plastic cups, and ultra-

bright photocopy papers. Many white fabrics, like those used in cotton T-shirts, have been treated

with whiteners and will fluoresce strongly. Driver’s licenses and credit cards have hidden marks

on them that show up only under UV. Some high-value postage stamps fluoresce green or red

(esp. airmail stamps). New $5, $10, and $20 bills (US) have thin fluorescent anti-counterfeit strips

in them. The location and fluorescent color of the strip varies from one denomination bill to the

next.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a

booth at a trade show), make up a larger “dark-box” with two or three view ports. I’ve also found

that it is best to use one of the strong high-output UV lamps manufactured by companies such as

Way Too Cool, Inc., or UV Systems, Inc. (See the web page of the Fluorescent Mineral Society

www.uvminerals.org for dealers that sell these and other lamps.) These lamps are available with

long-wave and short-wave UV bulbs. Although they are expensive, these lamps can be used for

a wide variety of demonstrations and they will give good results even with minerals that are only

weakly fluorescent.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Light Pipes and Frosted Rocks



Object: Fiber optic technology is the

basis of our modern computer

and telephone networks. Few

people know that natural fiber

optic materials occur in the

mineral kingdom. Students

can observe the fiber optic

effect in minerals such as

ulexite (“T.V. Stone”). This

effect depends upon the

phenomenon of total internal

reflection. Students use a

point light source and a frosted

piece of quartz to observe total

internal reflection.



Procedure description: Students place a piece of a fiber optic mineral such as ulexite on a white

piece of paper. Use a cut and polished slab of ulexite. Words written on the paper will appear to

jump up to the upper surface of the ulexite. Move the specimen across the page – notice how the

text appears to stay still while the specimen moves. Put the stone on a colored image. Note that

the stone also transmits color to its upper surface.



Students also place a piece of frosted quartz on a point light source. The entire frosted surface of

the quartz appears to glow.



Specimens to test: For fiber optic effect: fibrous ulexite (also known as “T.V. Stone”); fibrous

gypsum; fibrous trona. Flat surfaces, perpendicular to the fiber direction, must be cut in these

minerals. Polishing the surfaces is very helpful. Cutting and polishing these minerals is difficult

because they are all water-sensitive. Cut and polished specimens of ulexite are available from

mineral dealers and science supply houses.



For total internal reflection: a piece of quartz (single crystal) with a frosted exterior surface works

well. Frosted quartz can be made by taking chunks of clear single crystals and tumbling them in

a rock tumbler with coarse grit. This will eliminate any sharp edges and give the crystals a milky

white appearance. Then chip or polish a small window in the surface. This window should be just

sufficient to allow light from your light source into the crystal.

Light Pipes and Frosted Rocks Page 2 of 2



Equipment needed: Paper with crisp clear black on white lettering (larger lettering is best),

paper with clear colored figures or images. A small point source of light. A pen light that

uses a single LED (light emitting diode) is a good source of light. Colored LEDs are most

impressive.



Scientific discussion: Light that enters a transparent mineral reflects off the inside of the

mineral’s surfaces again and again, bouncing around the entire inside of the crystal. If the

exterior of the crystal is frosted, the entire surface will glow uniformly and some of the light

leaks out.

If light enters a long skinny transparent fiber, it will ricochet back and forth off the inside walls

as it travels down this light pipe. We rely upon this effect to transmit pulses of light down great

lengths of optic fibers.



The fiber optic effect can occur in ulexite, gypsum, and trona because these minerals grow in

long thin fibers. Light passes though the natural fibers in the same manner as it travels through

a synthetic optical fiber: it bounces off the interior of the sides. If the fibers are aligned parallel

to each other in sufficiently large clusters, the cluster can transmit an image that is larger than

any given fiber.



Additional possibilities: It is possible to acquire synthetic fiber optic material for demos.

Rough chunks of fiber optic material are sold to lapidaries. This synthetic material is dyed

(red, yellow, green, blue, etc.) and cut into the form of spheres, eggs, and other shapes for sale.

It is easy to identify the orientation of the fibers and use these materials to demonstrate the fiber

optic effect.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as

at a booth at a trade show), I’ve found that it is simplest to use a light source made from one of

the LED-illuminated display stands used for laser-etched glass paperweights. Some of these

display stands have multiple colors of LEDs and cycle through them. Take the paperweight

off the stand and use black electrical tape to mask off all but a small hole through which light

from the LEDs can shine. When you place the polished window of your frosted quartz directly

over the light hole, the entire stone will glow with the colors of the LEDs. You can just place

the frosted quartz on the masked stand, turn on the LEDs, and let the demonstration operate

by itself.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Wild and Cool Colors



Object: Everyone knows the

fascinating play of colors

that mark a good fire opal.

A variety of minerals

exhibit similar interesting

optical effects such as

schiller, iridescence, and

pleochroism. Students can

observe these properties in

hand specimens.



Procedure description: The procedure

is very simple: students pick

up stones, look through them

and observe their colors.

What colors are observed? Does the color change dependent upon direction? Hold them under

and incandescent lamp, then a fluorescent lamp. Do the colors change?



Specimens to test: Blue labradorite (a plagioclase feldspar) can show fascinating displays of

schiller (you can get large chunks or this material from the scrap yards of stone cutters who

make stone kitchen countertops or monuments). Opal and iris agate display iridescence (rough

scraps of low-grade opal can be purchased at many mineral shows). Iolite (variety of cordierite),

kunzite (a variety of spodumene), and other minerals show pleochroism. Alexandrite (a variety

of chrysoberyl) shows the alexandrite effect but can be very expensive – a cheaper substitute is

to buy rough chunks of synthetic “alexandrite effect” doped glass (also often for sale by lapidary

suppliers at mineral shows).



Equipment needed: A small, high intensity incandescent lamp is best for viewing effects such

as iridescence, pleochroism, and schiller. For the alexandrite effect, you’ll also want a small

fluorescent (white, not UV) lamp.



Scientific discussion: Iridescence in opal and iris agate is caused by the diffraction of light

(breaking of white light into its constituent colors). In opal, light is diffracted by the many

small silica spherules that make up the opal structure. In iris agate, light is diffracted when the

spacings between the fine bands of the agate are close to the wavelength of visible light. A similar

diffraction effect called “schiller” is seen when the lamellae (fine plates having different chemical

compositions) within the structure of the feldspar labradorite are fine enough to diffract light.

Wild and Cool Colors Page 2 of 2





Pleochroism is observed because the light moving through a crystal can be absorbed

differently depending upon the crystallographic direction it is following. Isometric (cubic)

minerals cannot show pleochroism, and in most other minerals any color differences are

impossible to see. But some minerals (such as kunzite, the pink variety of spodumene)

exhibit distinctly different colors or shades when looked at from different directions. The

iolite variety of the mineral cordierite is trichroic. Small samples can be purchased that

have been cut into cubes to maximize the trichroic display. When you hold one of these

cubes up to a light and look through it in one direction, it appears dark blue or violet, in

another direction a lighter blue, and in a third direction it is yellowish-gray (brownish).



The “alexandrite effect” is different than pleochroism in the alexandrite effect depends not

on the viewing direction but upon the color of the incident light. Fluorescent lights tend to

give off more blue light and incandescent lights give off more yellowish or reddish light.

Alexandrite (a variety of the mineral chrysoberyl) absorbs these lights differently. Thus it

appears blue-green in daylight or under a fluorescent lamp and red under an incandescent

lamp or a candle.



Additional possibilities: Rotating a polarizing screen between the light and a stone will

help accentuate the pleochroic effect.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors

(such as at a booth at a trade show), it is best to attach your specimens to a small cardboard

panel. It is difficult to secure a small polished cube of iolite that allows one to still look

through it in all directions, so you’ll just have to keep an eye on the specimen,

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.





How to Bend a Rock



Object: Students think of rocks as hard,

inflexible objects but it is possible for

them to actually bend a rock or a mineral.

Some rocks and minerals are elastic.



Procedure description: Students take a

piece of mica and try to bend it. Then,

using their fingernails, they pry off a thin

sheet. They’ll find that they can bend

the thin sheet. A notched drill core can

be flexed by squeezing its ends together

between a finger and the thumb.



Specimens to test: Mica – get as large of plates as possible. Notched drill core of a competent rock.



Equipment needed: How to make a fletched drill core: Find a piece of drill core between 10- and 20-inches

in length, the longer, the better. Select drill core that was cut from a competent rock. Using a diamond

saw, cut a thin slot down (the notch) the length of the drill core, stopping at least three or four inches from

the end. Experiment with different rocks, esp. metamorphic rocks. It may help to use core in which the

grain direction or layerings are parallel to the drill core’s length. You can demonstrate flexibility in a rock

by gentle squeezing the notched end of the core – the two halves will move together somewhat under the

pressure from your fingers and thumb. Don’t overstress the material (it is a good idea to prepare backups

– eventually they will break).



Scientific discussion: Every material is flexible to a small extent, even solid rocks. By cutting a long or

thin enough piece of a rock you can observe its flexibility without breaking it. Elastic rocks and minerals

not only bend, but they spring back, too.



Additional possibilities: Flexible sandstone (also called itacolumite) has been reported in Georgia, North

Carolina, India, and Brazil. A thin plate of flexible sandstone can be held between both hands and gently

flexed. Flexible sandstone is flexible for two reasons: it has often has small oriented plates of flexible

mica in it, and the grains of sand are interlocking but poorly cemented together. Some mineral dealers sell

flexible sandstone.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such as at a booth at

a trade show), I’ve found that it is simplest to use large thin sheets of mica. Kids can pick them up, look

though them, and bend them without damaging them. You should recognize that a notched drill core or a

piece of flexible sandstone will have a limited life span on a demo table. Bring back-ups.



Special Note: Many fibrous minerals are flexible. Asbestos minerals such as chrysotile are flexible, but

health hazard concerns preclude their use in most demonstrations.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Can you find the real diamond?



Object: If you purchase diamond jewelry, how do

you know you’re buying a real diamond?

Students will learn how difficult it is to

pick out a real diamond from among

fakes. If diamond simulants are hard to

distinguish from real diamonds, should

you spend lots of money on real gems?



Procedure description: Use a diamond tester. Test

a number of likely-looking specimens.

First, the student looks at the specimens,

then guesses which ones are diamonds,

and then uses the diamond tester to test

each specimen. Students will find that

many of the diamond fakes and simulants

are hard to detect.



Specimens to test: (all should be roughly the

same size) Faceted stones: inexpensive

diamond(s), small (0.1-0.2 carat are

fine) – can sometimes be obtained from

old inexpensive jewelry; moissonite;

quartz; rhinestone(s); cubic zirconia;

clear aluminum oxide, or other clear or light-yellowish gemstones. Rough, uncut materials:

diamond crystal(s); diamond(s) as chips or grit (may be obtained from old diamond drill

bits); bort; carborundum; moissonite; quartz; Herkimer diamond; glass; cubic zirconia;

other clear synthetic rough. Ideally all of the specimens would be small and roughly the

same size as your true diamond(s).



Equipment Needed: One electronic diamond tester. One of the old-style thermal conductivity

probes is best – ask a jeweler to loan/give/sell his old one – many jewelers had to buy new testers

because the older probes could not separate moissonite from diamond. Specimens should be

adhered to a wooden board. A dark stained hardwood is best. Faceted specimens may be glued

to the board – first make a dimple in the wood with a large nail or the tip of a pointed chisel, then

glue faceted specimens in place with epoxy glue. Rough material should also be attached to the

board.

Can you find the real diamond? Page 2 of 2



Ideally, you will have up to a dozen cut and a dozen rough stones with at least one real rough

and one real cut diamond. Number each specimen to permit guessing. Keep a separate list

for specimen identification.



Scientific discussion: Diamonds have a high index of refraction and exhibit strong dispersion

of light. And they are the hardest substance known. While, it is impossible to find or make

a simulant that does as well as diamond in all of these areas, it is possible to make synthetic

stones that appear similar to diamond even though they are substantially softer. The most

recent addition to a long line of diamond simulants is moissonite or silicon carbide. Most

silicon carbide, produced for abrasive purposes, is black, but new techniques allow the

production of clear colorless stones, suitable for faceting into “fake” diamonds.



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such

as at a booth at a trade show), just let them use the probe on their own to test the various

samples. You may wish to prepare a separate display of natural, synthetic, and fake rubies,

sapphires, and emeralds. The diamond tester is, of course, useless for test these stones, but

your visitors will have fun trying to pick out the real, natural gems.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Object:

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.Object: Students can

process a raw mineral, vermiculite, into its expanded or exfoliated form. By heating the vermiculite

they’ll see how physical changes can be related to the mineral’s structure.



Procedure description: Students take a small piece of unexpanded vermiculite, holding it with

tongs or long tweezers, and insert it into the flame of a propane torch. The vermiculite

expands rapidly to many times its

original thickness.



Specimens to test: Unexpanded vermiculite.

Equipment needed: Propane torch with narrow

tip (use clean, uncorroded tips);

propane tank; long pair of tweezers

(10 inches) or laboratory tongs; small

metal pan or tray, safety glasses or

goggles; fire extinguisher.



Scientific discussion: Vermiculite is a hydrated

mica. The name vermiculite is derived from

the Latin root vermi (worms) or vermiculare (to

breed worms), which is descriptive of the way

vermiculite looks when heated: the fragments

writhe about like worms.



Vermiculite expands for much the same reason

that popcorn pops. In popcorn, water vapor

pressure inside the kernel builds up as it is

heated. The water flash boils when the outer

shell cracks a little and the resulting explosive

boiling blows the kernel open. Vermiculite, like all micas, is a sheet silicate. When heated, water

between the layers of the vermiculite expands and pushes the sheets apart (to the point where the

water vapor can escape).



Expanded vermiculite can be dozens of times thicker than the original unexpanded mineral. The

sheet push apart and the result is a drastic increase in surface area (which helps its ability to absorb

chemicals).



Additional possibilities: It is possible to heat several pieces of vermiculite at the same time by

employing a stainless steel tea strainer (the kind that have a long handle with a wire mesh spoon).

Put a teaspoon worth of unexpanded vermiculite in the strainer and hold the mesh in the propane

flame. You’ll see the whole batch of vermiculite begin to exfoliate and squirm around – it never

fails to impress students.

The Popcorn Mineral Page 2 of 2





An interesting classroom lab exercise is to weigh the vermiculite with an accurate balance

before expansion and then again after expansion. Next, students can put the vermiculite

in water to see how much water it absorbs. It is important to shake off the excess surface

water before weighing to get an accurate measure of the absorbance. Does the expanded

vermiculite absorb more or less water than it lost upon expansion?



Notes for demo tables: If you are doing demonstrations for large numbers of visitors (such

as at a booth at a trade show), I use a chemical hot plate because of concerns about open

flames. To be effective, a hot plate must be turned up high. I spread a spoonful of unexpanded

vermiculite on the hot plate and within a minute the material will start to expand, looking

like a bunch of writhing worms. I made a wire mesh barricade (from an old wire mesh trash

basket) to keep kids hands away from the hot plate. After the vermiculite is expanded, I use

a spatula to scrap it into a tray. It cools quickly and I let kids take samples of the material.

Typically, I put the exfoliated vermiculite in a small (two-inch by two inch) zip-lock bag for

the students to take home. (It is harmless and it cannot be reused.)



Special notes: It is always a good idea to have a fire extinguisher handy when working with

flames.

“Minerals that do things…”

Hands-on demonstrations of mineral properties

Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.







Notes on sources of minerals and materials



How to acquire demonstration materials: Minerals, materials, and equipment useful for “Minerals

that do things…” can be acquired from a variety of sources. You do not have to spend a lot of

money to do good demos.



You can always go out and dig up your own rocks and minerals, of course, but what you find will be

a function of where you live. Mineral dealers are useful sources of educational minerals, but you

must make them aware that what you are seeking are low-end cheap specimens. You don’t want

to buy expensive specimens that will be damaged during your demonstrations. Mineral shows are

a good place to shop for demo pieces. You can cruise the aisles and compare what one dealer has

with the next. Don’t be afraid to talk to a dealer, explaining that you are looking for inexpensive

materials for educational demonstrations. Sometimes a dealer will have just what you want stuck

away in a box under his sales table; sometimes he can refer you to a good source.



I like to check out junk shops and thrift stores for equipment. I’ve picked up cheap used alcohol

lamps, Pyrex measuring cups, used metal files, plastic buckets, salad tongs, magnifying glasses,

radioactive Fiesta Ware, old alarm clocks with radium dials, and dozens of other things useful

for demos. Hardware stores are good sources for propane torches, steel wool, chisels, hammers,

safety goggles and other useful tools. Even grocery stores sell useful chemicals (for instance, salt

substitutes = sylvite). Often I get ideas just walking up and down store aisles.



Science supply houses: Science supply houses will also provide many of the minerals, materials,

and equipment, used in these demonstrations. Here are some that I’ve used:

American Science & Surplus 888-724-7587 www.sciplus.com

Carolina Biological Supply Company 800-334-5551 www.carolina.com

Edmund Scientific’s 800-728-6999 www.scientificsonline.com

Educational Innovations, Inc. 888-912-7474 www.teachersource.com

Ward’s Natural Science 800-962-2660 www.wardsci.com



Web sites: Many helpful mineral web sites can be found, including:

The Fluorescent Mineral Society www.uvminerals.org

MinDat www.mindat.org

The Mineralogy Database www.webmineral.com



Substitution: The key to keeping demonstration costs down is flexibility. Keep costs down by

substitution and borrowing. For instance, I’ve found that my household propane torch works well

enough for copper and strontium flame tests – it isn’t perfect for all tests – but I already own one

that I can press into service when I’m not fixing the plumbing.

Notes on demonstration techniques



For the novice: A demonstration is about performance as well as science. A little bit of flair and a

little bit of personalization will make your demonstration memorable.



Flair can be as simple as donning a lab coat and safety glasses before your demos. (Somehow,

a lab coat makes anyone look like an expert.) You don’t need an Einstein wig but you want to

communicate that you enjoy what you’re doing. Speak as though you’re really interested in what

you are saying (modulate your voice, accentuate the important points, etc.), and look directly at

the person your addressing as much as possible. Pick out the shy kids in a crowd and bring them

forward to try the demos. It takes work but it will be fun!



By personalization, I mean that you must tailor what you say and how you say it to the immediate

audience. If you’re doing a salt taste test for pre-schoolers, taste the salt first yourself, then make

a face. Some will be brave and follow your lead, others will be shy. That’s OK. It’s fun to make

Mom or Dad or their teacher try the taste test if their youngsters are shy. Once the taste the rock

salt, explain that this is the same stuff we put in a salt shaker and that every time they salt their

French fries they’re putting a mineral on their food. At demonstrations for adults you can ad in

more detailed explanations of the science behind the demo. One important note: don’t assume

that adults have seen these all demos before – most people, even many geologists, have never seen

tenebrescent hackmanite or tasted hanksite.



If you are doing a number of demonstrations at a time (such as you might at a trade show or

mineral show booth) you should make up signs with a few sentences of explanation. Answer some

of the common questions (what is this mineral? what is it used for?). Specimen labels and signs

are important. They save your throat at the end of the day because you won’t have to repeat an

explanation over and over to each new visitor.



Having an assistant or two can be critical to a successful demo. Work as a team, when one

demonstrator is talking, the other can be preparing the next demonstration or talking to another

group of visitors.



You also need adequate space: two or three tables minimum at a booth with a back table to keep

some supplies out of reach. Don’t get too crowded, especially if you are doing flame tests, using

hot plates, or hitting minerals with hammers.



Try to keep your demo table neat, clean and uncluttered. You’ll be surprised how quickly a booth

or a classroom can get messed up. When I’m doing salt taste tests, or vermiculite exfoliations, I’m

soon up to my elbows in mineral chips and dust. A small portable

“Dust-Buster”-type vacuum helps keep the mess under control. When a lull in traffic occurs at

your booth, take a moment to vacuum up.



If possible, give away free samples. Even mundane rock samples can look good if put in a small

zip-lock baggie with a neatly printed label. Put the name of your company on the labels, too.

(Note: the give-aways don’t have to be your own company’s products.)