Guide to Gemstones

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					 Guide to
Gemstones
Agate
The gemstone Agate is distinct from other forms of gemstones and is one of
the widest source of colours chalcedony. Agate occurs in a variety of forms
Agate has many colors. Agate mentioned in the Bible as being one of the
stones of fire given to Moses and set in the breastplate of Aaron. A variety of
agate, sardonyx is one of the twelve gemstones set in the foundations of the
city walls of Jerusalem. Agate was especially valued during medieval times
when one of the more outlandish uses was to bind an agate to each horn of
an ox to ensure a good harvest. The danger here is that your agated beasts
of burden may then become invisible and a little hard to find. Agate is
believed to cure insomnia, offer protection from bad dreams, ensure pleasant
dreams, protect against danger and promote strength and healing. The most
famous of the european Agate mines where in Germany in Idar-oberstein
these mines have now been worked out but can be chased back as far 16th
century. The most important depsoits today are Brazil, and Uruguay as well
as depsoits in
Austrlia,China,India,Madagascar,Mexico,Mongolia,Namibia,United states as
well as small depsoits being found around the world.

Amber
Amber is is tree resin that has fossilized. The oldest amber found to date is
320 million years old. It has always been prized as both decorative peaces as
well as for as for healling and also in the past as a for of oil as heating will
soften it and then eventually it will burn. If melted and added to turpentine or
linseed oil it can become an amber varnish.
Amber is better know today for it beauty as a form of gem when polished it is
a cheap but sought after stone. Found in different depsoits world wide the
European depsoits found along the Baltic coast line this has been traded for
over 2000 years and is still today. There are large depsoits in China as well as
a blue variety found in the Dominican Republic.
It is also found in New Zealand specifically in coal seams there this is called
Ambrite. Amber has in recent years caused great stirs in sceince as many
bugs and insects found trapped in Amber have been found to still contain
DNA. This Amber is highly prized by collectors and fetchs a high price on the
market.
Amber now has many synthetic and many are made containing all manner of
bugs creatures which would never have been able to become trapped in the
resin. One of the most famous things made from amber was the Amber Room
in the Catherine Palace in Saint Petersburg, Russia. An intire chamber
decorated and made of amber panels backed with gold leaf and mirrors. This
room and what happened to it are one of the biggest mysterys of world war
two the room was stolen by the germans and shipped away and then in the
chaoes of the end of the war it was hidden some say destroyed but nobody
knows for sure. A copy of this room has now been made and is back in the
palace. The original covered more than 55 square meters and contained over
six tons of amber . Many small musems have large collections of amber and
some whole musems are dedicated to it completly in the former soviet block
including Latvia And Estonia

Amethyst
Amethyst is one of the mineral quartz (SiO2) with light purple to dark purple,
The name means not drunken in greek as was worn as a amulet against
drunkeness, Tabak," commonly used as jewelry. Amethyst is beautiful light
purple to dark purple. It has served as a symbol of royalty throughout history
of adornment can be traced back to the Minoan period in Greece . Pharaohs,
kings and queens, as well as leading lights in religious sects have long
treasured it because of its rich, royal color. Interestingly, this fascination with
the color purple dates back to Roman times when generals celebrating
triumphs got to wear a toga dyed the colour of Amethyst. Colored by an
interaction of iron and aluminum, Amethyst is a variety of macrocrystalline
quartz that occurs in transparent pastel roses to deep purples and violets.
Now days Amethyst is also availible in green this is due to heating changing
the colour from purple to green. It has a mohls hardness of 7 and a refractive
index of 1.544-1.553

Ametrine
Amentrine is colour zoned quarz being made up normally half and half of
Amethyst and Citrine ( Citrine is naturally heated Amethyst which then
changes from purple to yellow) The best know depsoits today are Brazil and
Boliva.

Andesine
Andestine is a lesser know gemstone but is becoming more popular due to
larger depsoits being found and worked. It comes in a range of colours from
red to pink and also white, gray,yellow, and green it also ranges from opaque
to transparent with the opaque the more common. It has a mohls scale of 6-
6.5 and has refractive index of 1.543-1.551

Apatite
Apatite means cheat in greek because it can be easily confused with many
other gemstones the most common of which today for the blue would be
Zircon. It is availible in blue and also green, pink and yellow and also violet
the light green of this is called asparagus stone due to the colour. This gem is
found in many depsoits worldwide and is commanly availible. It has a mohls
hardness of 5 and a refactive index of 1.628-1.649.

Aquamarine
Although a Beryl Aquamarine as well as emerald fall under there own
catogory of gem and are not grouped into the precious beryl group.
Aquamarine is named afer the latin for seawater. The most popular colour is
dark blue which is caused by iron being present when formed the best mine
for this colour was santa Maria in Brazil and this top colour gem is sometimes
known as this regardless where it came from. It is known for lower qualities
to be heat treated to enhance the colour and in some case neutron and
gamma radiation but this type of treatment is known not to last. Aquamarine
is brittle and sensitive to pressure so great care must be taken when setting.
It has a mohls hardness of 7.5-8 and a refractive index of 1.564-1.596

Aventurine
Aventurine is a natural type of glass also called aventurine quartz italian
meaning a ventura. Found in Green, Redish brown and golden brown colours
it has a mohls hardness of 7 and a refractive index of 1.544-1.553. Depsoits
of this are found worldwide and is used in many forms from beads to
cabochons for jewellery
Beryl
Precious beryl refers to all in that group that are not Aquamarine, Emerald.
Beryl comes in a wide range of colours and is found in depsoits worldwide
some of the better known varieties are Golden beryl, Goshenite, And also
morganite because of this the colours also range widely as well as from
opaque to transparent. Its mohls hardness is 7.5-8 with a refractive index of
1.562-1.602

Calcite
Calcite also know as limespar, limestone is found in a range of colours also
ranging from transparent to translucent. It is a quite soft gem ranging at only
3 on the mohls hardness scale so great care must be taken when working
with this item. It refractive index is 1.486-1.658. It is widely found worldwide
but due to the softness is rarely faceted and then only for collectors as
normally to brittle for setting.

Chalcedony
Chalcedony is the name used by gemologist for all cryptocrystalline quartz.
Natural Chalcedony normally has no banding but because it is porous it is
possible to dye this gem to colours not found naturally. Other well known
gems that come in this group are carnelian and sard. This is normally found in
either cabochon cut of sliced and polished similar to agate. It has a mohls
hardness of 6.5-7

Chrome Diopside
Chrome Diopside is found in depsoits around the world but due to small
crystals is rarely found in large sizes. The deep green colour is caused by rich
chromium depsoit when the crystal formed causing this deep green. Although
there is a very rare varity found in italy called violan. The largest depsoits yet
found are in sibera and smaller sources in europe and the US and Canada. It
has a mohls hardness scale of 5-6 and a refractive index of 1.66-1.72.

Chrysoberyl
Chrysoberyl the name is from the greek meaning golden although is found in
a range of colours rangeing from yellow to green. The gem varieties are
amongst the worlds rarest gems with Alexandrite coming under this heading.
Whilst nearly always faceted a cat eye cabochon is also found and the name
only cats eye gem refers to this gem alone all others should have there name
after cats eye I.E cats eye quartz. This is a hard wearing gem that makes it
ideal for jewellers. Mohls hardness of 8-8.5 the refractive index for this gem
is 1.746-1.763. Most depsoits of this gem are now worked out and the others
finding less of gem quaility.

Chrysocolla
Chrysocolla is normally found in copper mines in arid areas. It is found in
copper veins. it is sometimes used as an alternative to turquoise. The name
first appears in 315 bc and comes form the greek name chrysos for gold and
kolla for water. Chrysocolla forms as crusts and stalacites. Chrysocolla is soft
and tends to break unless intermixed when forming idealy with quartz and
chalcedony which gives it duribillity and enables it to be worked. Found
through out europe the US and africa with a mohls hardness of 2-3 and a
refractive index of 1.58-1.64
Chrysoprase
Chrysoprase is considered the most important gem in the chalcedony group.
The name in greek means gold leek. the colouring agent for this gem is
nickel. It is found worldwide but now belived to be worked out in Poland.
Naerly always found in cabochon cut a few examples are founf faceted always
opaque to translucent. It has a mohls hardness of 6.5-7 and a refractive
index of 1.530-1.540.

Citrine
Citrine the name is derved from its yellow colour. This gem is rare as a
natural citrine as most are heat treated amethyst although there are a few
depsoits that have natural citrine worldwide. Its colour is caused by iron as a
colouring agent when forming. Natural citrines are usually pale yellow. It has
a mohls hardness of 7 and a refractive index 1.544-1.553

Crystal
Crystals is a solid substance in which the molecules, atoms, or ions are
arranged in an orderly repeating pattern extending in all three spatial
dimensions. The word crystal is a loan from the ancient Greek word. Crystals
are often symmetrically which had the same meaning, but according to the
ancient understanding of crystal. At root it means anything congealed by
freezing, such as ice. The word once referred particularly to quartz, or "rock
crystal"

Demantoid
Demantoid is the green gemstone variety of the mineral andradite, a member
of the garnet group of minerals chromium is the cause of the demantoid
green color. While garnets have been known since ancient times, the
demantoid variety was not discovered until 1853. Today many countrys have
been found to have depsoits including Russia and Namibia, demantoids are
also found in other locations including Italy (Val Malenco, Lombardy), Iran
(Kerman) and Afghanistan In around 2009, there was a significant discovery
of demantoid and andradite garnet in Madagascar. Mohs scale hardness 6.5-
7.0 Refractive index 1.880 - 1.889

Emerald
Emerald Deep green beryl is known as emerald. the name derives from greek
smaragdos and means green stone. Emerald is the most precious gem in the
beryl group and as such is the most sought after. The coloring agent for real
emeralds is chrome but a lesser emerald is coloured by vanaduim although
this should be called green beryl but most people still call it emerald.All
emeralds are brittle and must be treated with care. Most emeralds are
enhanced by oiling which can be done before cutting or after most rough
gemstones will be placed in oil to await cutting. It has a mohls hardness of
7.5-8 and a refractive index 1.565-1.602. Found mainly in central america
and Africa with the most sought after being from Colombia especially the
muzo mine northwest of Bogota. Emeralds have also been found in Russia
and other countries but the quaility is lesser than that of cetral america nad
africa
Fluorite
Fluorite from the latin fluere.. An eye catching feature of fluorite is its
distinctive multicolored banding. Fluorite, from which we get the word
fluorescent, crosses the entire color spectrum from deep purple to crimson
red, blue to green and also chrome fluorite and frosty orange to lemon
yellow. Mined in England as well as other countries Fluorite is one of the more
famous fluorescent minerals. Many specimens strongly fluoresce in a great
variety of colors. Due to its glassy luster fluorite is highly coveted. Fluorite is
the natural crystalline form of calcium fluoride and often forms beautiful
cube-shaped crystals. It is a transparent to translucent mineral. When pure,
fluorite is colorless; however, it usually contains impurities (minerals that
color it). The most common colours are violet, blue, green, yellow, brown,
pink. It has a mohls hardness scale of 4 and a refractive index of 1.434

Garnet
The garnet group is a wide a varyied group. The name derives from the latin
meaning grain due to the rounded crystals . Garnet is normally known as red
but many other colours also fall under this heading some being found in only
a few depsoits in the world such as tsavorite named by Tiffany and co after
the Kenyan national park where found. It is also found in tanzania and has
also been found in madagascar. Most have the same mohls hardness of 6.5-
7.5 but the refractive indexs are different for each type of gem.

Hematite
Ancient Egyptians used hematites as ornamental objects placed inside their
tombs. Hematite derives its name from the Greek word haem (blood ) in
allusion to its red color in its rough form. Deposits: The most important
deposits of hematite come from a sedimentary deposit: the Lake Superior
district in North America. Other important deposits include Minas Gerais
(Brazil), Cerro Bolivar (Venezuela), Labrador, and Quebec It Has a mohls
hardness of 5.5-6.5.

Hessonite
Hessonite garnet is the Jyotish gem related to Rahu which is mainly an
elemental and instinctual entity. When badly positioned, this "shadow planet"
is characterized by insatiable worldly recognitions and desires together with
sense gratification. Wearing a hessonite of at least 2 carats is said to bring
success, wealth and notoriety in society, increase life span and good fortune.
Hessonite can be substituted with orange zircon.

Hiddenite
Hiddenite was named after A.E hidden who discovered this gem in North
Carolina. Its colouring agent is chromium and will fade after time time in
sunlight. Its colours range from emerald green to yellow. It has a mohls
hardness of 6.5-7 and a refractive index of 1.660-1.681

Iolite
Iolite Also called Cordierite and Dichroite. The name comes form the greek
word violet. Inclusions of Hematite and goethite can cause a reddish sheen. It
has a mohls hardness of 7-7.5 and a refractive index of 1.542-1.578 Depsoits
of this gem are rare found in Myanmar, Brazil, India Sri lanka and more
recently in Madagascar.
Jade
The English word is derived from the Spanish term piedra de ijada or "loin
stone", from its reputed efficacy in curing ailments of the loins and kidneys.
In some countries, jade is more commonly known as 'greenstone'. most Jade
is from China or Myanmar it is normally cut into cabochon on flat polished
peices due to its toughness to work with. It has a mohls hardness of 6.5-7
and a refractive index of 1.652-1.688

Jasper
Jasper is normally considered a chalcedony the name is from greek and
means spotted stone. It is found in a varity of colours and is made up of
nearly 20% of foregin materials. used mostly for ornamental objects in can be
found in cabochon and sliced polished forms for jellery and Beads. The
stripped banded varity has a tendence to split along the bands. Uniformly
coloured jasper is rare found normally multicoloured or with strips. Its mohls
hardness is 6.5-7 and has a refractive index of about 1.54

kunzite
kunzite named after G.F Kunz. It mostly a light pink being coloured by
manganese when formed. This gem is also affected by sunlight and can fade.
Also found in a brownish and green violet rough these later to are normally
heated to turn the gem a light pink colour often confused with morganite. It
has a mohls hardness of 6.5 and a refractive index of 1.660-1.681. The main
producer is Brazil but other depsoits are found worldwide

Kyanite
Kyanite also called Disthene gets its name from the greek meaning blue. It is
difficult to cut because of variable hardness often found with irregular streaks
in it which can effect the colour looking like cracks in it. it has a mohls
hardness of 4.4.5 along the axes and 6-7 across the axes. It has a refractive
index of 1.710-1.734 this gem is found in several deposits worldwide

Labradorite
Labradorite Named for its scource on Pauls island near the town of Nain
labrador Canada. It is also know as spectrolite and madagascar moonstone It
occurs in large crystal masses in anorthosite and shows a play of colors called
Labradorescence. Other sources are norway and Finland but Canada is the
largest known to date. The refractive index is 1.559 to 1.570 the mohls
hardness scale is 6-6.5

Lapis Lazuli
Lapis Lazuli is a relatively rare semi-precious stone that has been prized since
antiquity for its intense blue color. Lapis Lazuli is still mined today in
Afghaistan Badakhshan province. Lapis lazuli has been collected from mines
in the west hindu Kush mountains in Badakhshan province of Afghanistan for
over 6,000 years and there are sources that are found as far east as in the
region around Lake Baikal in Siberia. Trade in the stone is ancient enough for
lapis jewelry to have been found at Predynastic Egyptian and ancient
Sumerian sites, and as lapis beads at neolithic burials in Mehrgarh, the
Caucasus, and even as far from Afghanistan as Mauritania. It is also found in
Angola, Myanmar, Canada, Pakistan, and the USA It has a mohls hardness of
5-6 and a refractive index of about 1.50
Moonstone
Moonstone is a member of the feldspar group. This gem is always cut in
cabachon to give a nice moonshine colour hence the name. Moonstone is
composed of two feldspar species, orthoclase and albite. The two species are
intermingled. Then, as the newly formed mineral cools, the intergrowth of
orthoclase and albite separates into stacked, alternating layers. When light
falls between these thin, flat layers, it scatters in many directions producing
the phenomenon giving the effect of moonlight. It has a mohls hardness scale
of 6-6.5 and a refractive index of 1.518-1.526

Morganite
Morganite is a rare light pink to rose-colored gem-quality variety of beryl and
comes under the heading of precious beryl. Named after financier and gem
collector J. P. Morgan. It has amohl hardness of 7.5-8 and a refractive index
1.562-1.602

Nuummite
Known to be “The oldest mineral in existence”, Nuummite is a laminate, or
sheet of compressed rock. It is found in an area north of Nuuk, Southern
Greenland. The area in which it is mined is accessible by boat only, in an iron-
ore region which dates back over 4 billion years. It Has a mohls hardness of
5.5-6. It is normally worked as cabochon or as flat pieces to show the colours
off to best effect

Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive
igneous rock It is named after the roman Obsius. In the past used to make
Amulets and necklaces to protect the wearer from harm. It was also used in
the making of weapons as it is very hard. Pure obsidian is usually dark in
appearance, though the color varies depending on the presence of impurities.
Iron and magnesium typically give the obsidian a dark green to brown to
black color andsome stones, the inclusion of small, white crystals in the black
glass produce a blotchy or snowflake pattern which is know as snowflake
obsidian. it has a mohls hardness of 5-5.5 and a refractive index of 1.45-1.55

Onyx
Onyx is a type of agate but instead of having curved bands it has straight
ones. onyx comes from the greek meaning claw or fingernail because with the
bands it is said to resemble the growth lines of a finger nail. Natural black
oynx is rare so nearly all commercial oynx is black agate that has been dyed
and treated it has a mohls hardness 6.5 and a refractive index of 1.54

Opal
Opal comes from the indian Sanskrit word for stone. All opals contain water
between 3 and 30% and when this dries out it maybe possible to restore the
colour by saturation in oils or epoxy resin or water will in some cases restore
the opal to former glory. Opal is also sensitive to knocks and damage and if
has been heated easy to dry out and crack. Another form of treatment
common to opal is doublet or triplet opals which are a small thin peice of opal
backed by another peice of material to strengthen it then if a triplet a third
clear peice is placed over the top to to seal the opal. It has a mohls hardness
scale of 5.5-6 and a refractive index of 1.37-1.52
Peridot
Peridot was mined in Egypt for over 3500 years then forgotten and only
rediscovered in around 1900. The name derives from the Arabic faridat which
means gem. Now many depsoits of this gem are found worldwide with some
of the best still coming from the mountains in Pakistan but here it is only
mined for a few months a year due to the harsh weather conditions. Peridot
was brought to europe by the crusaders in the middle ages. There are some
cut Peridot which came out of a meterorite that fell to earth in eastern sibera
in 1749. It has a mohls hardness scale of 6.5-7 and a refractive index of
1.650-1.703. Although Peridot in the past was found in large sizes it is now
becoming rarer to find peices over 10 carats

Prehnite
Prehnite was named after a Dutch Colonel h. von prehn. It is better know as a
collecters gemstone when included with rutile but is available without
inclusions and also a cats eye is know to occur. Again this gem is known to
fade in strong sun light. It has a mohls hardness of 6-6.5 and a refractive
index of 1.611-1.669

Rhodolite
Rhodolite Gemstone – see Garnet

Rubellite
Rubellite comes from the latin for reddish. Rubellite is a member of the
tourmaline group. It varys in colour from pink to red with the later being the
most valuable. It has a mohls hardness scale of 7-7.5 and a refractive index
of 1.614-1.666

Ruby
Ruby it wasnt until about the 1800s that ruby was recgnised as belonging to
the corundum family. The red colour of ruby varies from each depsoit. The
colouring agent is chromuim and the brownish tones found in some ruby is
because of iron also being present. Heat treatment of rubys is common and
now is almost standard as well as lead glass filling which is becoming more
and more common as the better quaility rubys become harder to find. Large
Rubys are rarer than diamonds and as such the price reflects that. with
depsoits worldwide this is one of if not the most popular gemstone pushing
even that of Diamond. About lead glass or cavity filled ruby this treatment
allows poorer colour or quaility rubies to be used in the production of
jewellery. The process is simple a glass powder is placed upon the rough ruby
and then heated becuase ruby is porous it sucks the molten glass into any
cavitys or cracks thus sealing them and enables them to be used as gem
quaility stones and also allows the price to be that much lower than an un
heated/treated gem thta the prices falls within anybodys budget. Rubies in
the past where belived to ward off misfortune and illness. It has a mohls
hardness scale of 9 and a refractive index of 1.762-1.778

Sapphire
One of the worlds best loved and known gemstones. It is in the corundum
species the same as Ruby with the same hardness and with the pink sapphire
can be very hard to tell apart.Trace amounts of other elements such as iron,
titanium, or chromium can give corundum blue, yellow, pink, purple, orange,
or greenish color. Pink-orange sapphires are also called padparadscha. Pure
chromium is the distinct impurity of rubies. However, a combination of e.g.
chromium and titanium can give a sapphire a color distinct from red.
Sapphires are commonly worn as jewelry. Sapphires can be found naturally,
by searching through certain sediments (due to their resistance to being
eroded compared to softer stones), or rock formations, or they can be
manufactured for industrial or decorative purposes in large crystal boules.
Because of the remarkable hardness of sapphires (and of aluminum oxide in
general), sapphires are used in some non-ornamental applications, including
infrared optical components, such as in scientific instruments; high-durability
windows (also used in scientific instruments); wristwatch crystals and
movement bearings; and very thin electronic wafers, which are used as the
insulating substrates of very special-purpose solid-state electronics (most of
which are integrated circuits).

Scapolite
Scapolite is named after the greek for stick. It has a vitreos luster pink and
violet cats eyes are also know in this gem form. Its refractive index is 1.540-
1.579 and a mohls hardness of 5.5-6


Sodalite
Sodalite refers to its soduim content. Only the blue varity of theis stone is
used in jewelry. Normally always found in cabochon form for jewelry and also
for ornamental stone. It has a refractive index of 1.48 amd a mohls hardness
of 5.5-6. There is a pink coloured varity from Canada called Hackmanite but
the colour will fade in daylight.


Spectrolite
Spectrolite is a rare variety of labradorite feldspar found in Finland. The
quarrying of spectrolite began after the Second World War and has become a
significant local industry. In 1973 the first workshop in Ylämaa became
cutting and polishing spectrolite for jewels.

Sphene
Sphene from the Greek sphenos meaning wedge. Sphene also know as
titanite. Titante can be changed to orange or red through heating. The
International Mineralogical Association Commission on New Minerals and
Mineral Names (CNMMN) adopted the name titanite and 'discredited' the
name sphene as of 1982, although commonly papers and books initially
identify the mineral using both names. Sphene was the most commonly used
name until the IMA decision. It has a refractive index of 1.842-2.110 and a
mohls hardness of 5-5.5

Spinel
Spinel is the magnesium aluminium member of the larger spinel group of
minerals.common crystal forms are octahedra. Spinel is found in many
colours and the most valuable is the burmeise red that can fetch in the US
upwards of $6000 per carat for the right colour and quaility. Large gemstones
are rare and also there is a star spinel that is very rare also. the refractive
index is 1.712-1.762. It has a mohls hardness of 8. The british crown has a
large spinal set in it that was thought to be a large ruby called the The Black
Prince's Ruby is a bead-shaped spinel weighing roughly 170 carats and has
been in the British Royal Family since 1400A.D

Sunstone
Sunstone was not common until recently. Previously the best-known locality
being Tvedestrand, near Arendal, in south Norway, where masses of the
sunstone occur embedded in a vein of quartz running through gneiss. Due to
the discovery of large deposits in Oregon, Sunstone is now readily available
with new sources being found and widespread through the USA. Sunstone is a
plagioclase feldspar. It has a mohls hardness of 6-7 and a refractive index of
1.525–1.58

Tanzanite
The name Tanzanite comes from Tanzania the only know source of gem
quaility. Tanzanite is normally heated to 752-932 degrees f to remove any
green or yellow tints this also darkens the blue colour. Green and pink
Tanzanite are extremly rare but do appear every now and then. The only
depsoit is in Tanzania near to Arusha. Other known transparent varitys do
exist. It has a mohls hardness of 6.5-7 and a refractive index of 1.691-1.700

Tektites – Meteorites
Where did tektites come from? There have been several schools of thought over
the last hundred years, but basically today it distills down to the Earth through
the impact of a meteorite or comet. In a cratering event, soil and rock are
liquefied, or vaporized. There is question as to how long the tektites took to form
and how high they were ejected. Was it a simple trajectory or did they travel high
nearly into space? It is clear that part of the time they traveled at very high
speed for they had to traverse great distances.

Current chemical analysis of tektites indicates that there is a relationship to rocks
only found on Earth. Fifteen rare earth elements have been used to show that
their relative abundances are in exact relationship to their abundance in tektites.
Melting a granite like rock will essentially make tektite glass composition.
Oversimplification but actually close since many sedimentary rock thought to be
used for tektites are derived from granites.

Tektites have been found with other artifacts in archaeological sites dating back
thousands of years. They have a long history of use and significance to man.
Ancient man in many places took advantage of the glassy nature of tektites and
used them for making flaked tools. Later, they were considered to have religious
significance in Asia, the colorful green varieties (Moldavites) of Europe have been
used for jewelry for hundreds of years and are making a return as gems today.

Tsavorite
Tsavorite Dr. Campbell R. Bridges dicovered this gem in 1967 ( he was murdered in
2009 after a long dispute over access and mining rights with local tribes)
Named after the first location that this gem was found in the Tsavo National Park in
Kenya. The only other known source for this gem is in madagascar. The colour is caused
by Trace amounts of vanadium or chromium that provide the green color.
It has a Mohs scale hardness 7 - 7.5
It is singulary refractive Refractive index 1.740
Unlike many other gemstones, the tsavorite is neither burnt nor oiled.
Only in rare individual cases is a raw crystal of over 5 carats found, so a cut tsavorite of
more than two carats is a rare and precious thing

Topaz
Pure topaz is colorless and transparent but is usually tinted by impurities; typical topaz is
wine, yellow, pale gray, reddish-orange, or blue brown. It can also be made white, pale
green, blue, gold, pink (rare), reddish-yellow or opaque to transparent/translucent. Some
imperial topaz stones can fade on exposure to sunlight for an extended period of time.
Naturally occurring blue topaz is quite rare. Typically, colorless, gray or pale yellow and
blue material is heat treated and irradiated to produce a more desired darker blue. Mystic
topaz is colorless topaz which has been artificially coated giving it the desired rainbow
effect. It Has a mohls hardness of 8 and a refractive index of 1.609-1.643

Tourmaline
Tourmaline The name comes from the Sinhalese word "Thuramali. The tourmaline group
is very varied and comes in many colours including bi and tri colour specimens. Other
sought after varients are indoclite and rubellite. This gem is often confused with many
others due to the number of colours it comes in. It has a mohls hardess of 7-7.5 and a
refractive index of 1.614-1.666.

Turquoise
Turquoise The name means Turkish stone as this was the route into Europe. Pure blue
colour is very rare as most is interspersed with other elements or intergrown with
malachite or chrysocolla. It is found in widespread depsoits but the best quaility is said to
come from north east Iran. This gem is very easy to damage so is bets taken off when
washing etc as this will effect the colour. House hold chemicals such as cleaners and
deturgents should be avoided. It has a mohls hardness of 5-6 and a refractive index of
1.610-1.650

Zircon
Due to its hardness, durability and chemical inertness, zircon persists in sedimentary
deposits and is a common constituent of most sands.Colour Reddish brown, yellow,
green, blue, gray, colorless; in thin section, colorless to pale brown. Natural green
zircon is caused by natural radiation and is the most sought after by collectors. It has a
mohls hardness of 6.5-7.5 and a refractive index of 1.810-2.024

				
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