Aug05 Friends NL.pmd by hjkuiw354


									Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005   1




What’s On?

Sunday, August 28th 2005
  Fossils of Permian age in Western Australia
  what they look like and where to see them.
where?         First Year Geology Lab., enter from Car Park 19, UWA
when?          12.30pm start for activities and talk.
Come a little earlier and bring a picnic lunch if you like: if it is wet you
can eat in the lab. (no strong-smelling foods please!): I will be in there
from 12.00 pm onwards.
what? There will be an illustrated talk and lots of hands-on material
to look at. Do you have any fossils and don’t know what they are? Why
not bring them in for me to have a go at identifying them for you, and
so we can all enjoy them.
2        Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005

                                                              Permian fossils from the
                                                              Carnarvon Basin

                                                      The lace-like patterns are the
                                                      skeletons of tiny colonial animals
                                                      nial called bryozoa, and the “angels
                                                      wing” is the shell of a brachiopod.
                                                      Although they have two shells like a
                                                      clam, the animal inside is totally
                                                      different from a clam, being
symmetri                                              symmetrical and having supports for
                                                      its respiratory apparatus.

SCIENCE WEEK talKS to looK out for:

                      Mon, 15 Aug 2005                         19:00
                      FREE LECTURE:                        “Our Sun”
    by Dr Mark Lofts, Astronomical Society of Western Australia

in the Kings Park Administration Building, Kings Park, off Fraser Ave,
Kings Park

Our Sun is halfway through its 10 billion year lifetime. Its reliable and steady
energy output - due to nuclear fusion - is attested by the evolution of
complex life on Earth. Nevertheless, the interior workings of the Sun such as
the 11-year sun spot cycle remain only partly understood despite new
observational techniques such as helioseismology.
In his presentation, Dr Lofts will touch on many aspects of solar astronomy,
describing and discussing the internal structure of the Sun, the Sun’s
rotation, its mass distribution, and will provide an explanation of the
perihelion shift of Mercury’s orbit from a different perspective.
      Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005   3

                          Tues 16th Aug                  19.30-21.30
  Meteorites - a Journey through Space and Time”
                          by Dr Alex Bevan, WA Museum
a Free Scitech National Science Week Event at Horizon the Planetarium,
Cnr Sutherland St and Railway Ave West Perth

                  Wed, 17 Aug 2005                        19:00
             A Hitchhiker’s Guide to Astronomy in WA
a Free RSWA National Science Week Event at Horizon the
Planetarium, Cnr Sutherland St and Railway Ave West Perth

Introduced by the Minister for Science the Hon Dr Judy Edwards, hosted by
the Royal Society of WA, the Astronomical Society of WA and Horizon the
Planetarium, RSWA members and guests, will be given an outline of the
research interests and activities of WA Astronomy scientists and the ASWA
followed by a Horizon Planetary Show. The event is free of charge, all
welcome (could well be booked out by now however).
Guest speakers (5-15 minutes duration) will be:
     Hon Dr Judy Edwards, Minister for Science
     Dr Alex Bevan, RSWA President,
“Blasts from the Past - a Tale of Asteroidal or Cometary Impacts”
     Mr Michael Allman, Astronomical Society of WA
“How the Ancient Greeks Measured the Circumference of the Earth
200 years BPE.”
     Dr Jaimie Biggs, Perth Observatory
“Past achievements and present activities of the State’s Observatory”
     Mr Alan Brien, CEO SciTech
Following a refreshment break, and display viewing,
The Horizon Planetarium show: “The Search for Life: Are we Alone?”
This hour-long show is billed as “A breathtaking show narrated by Academy
Award-nominated actor Harrison Ford. An exhilarating journey from the
depths of Earth’s oceans and onward to planets outside our Solar System,
The Search for Life depicts how scientists are searching, as never before,
for signs of life beyond our world”.
URL: For more information:
Margaret Broxx Horizon: Ph 94868246
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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _______________________
4      Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005

                                    SCIENCE FAIRS!!!
Some of our members enjoy the TripleS Science Fairs. These events
are put on for the public, but are especially designed to enthuse children
about science. All the local universities and science establishments come
together so that there may be fifty displays of interesting things, many hands-
on or with giveaways. Door prizes are also given throughout the evening.
I always put on something nice at these events. The next one is on
Tuesday, August 16th, in Science Week, at Carine SHS, Everingham
Street, Carine, parking off Osmaston Road. They are free to all, and
reasonably-priced food and drinks are available to purchase on the night:
they run from 5.30pm to 8.30pm.
✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸ ✸✸✸✸✸✸✸✸✸✸✸✸✸

Good websites to visit:
with this free download you can zoom in on anywhere on Earth: I got a
nice colour aerial shot of my house in Nedlands, plus you can “fly”
down the Grand Canyon and other exciting places.
(a bit fussy as to your computer, some people may not be able to load)
Go to “Products and Services” and then choose “Online Publica-
you can download many useful publications for FREE, including the
Field Guides for say the Northern Perth Basin (includes areas like
Gingin, Kalbarri, Coalseam Park) or the Southern Carnarvon Basin
(lots of detailed information on Kalbarri and areas north to Exmouth
and Cape Range).
for lots of exciting geological stuff, from pictures to talks.
       Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005   5

our laSt tWo ‘frIENdS’ MEEtINgS
Sunday, May 29th 2005
What is it Made of? a geological quiz and illustrated talk about
ornamental stones.

The last “Friends” workshop and talk, in May, gave us some interesting specimens of
worked, but natural stone, objects like carvings and bowls to look at and think about.
Some people brought their special treasures: we particularly admired the magnificent
lapis lazuli Buddha, one of the beauties which Helen brought for “show and tell”. I
had set up around fifty ornamental stone objects, ranging from statues to bowls and
ashtrays, around the room for a fun quiz: afterwards we sorted them out into their
various types and discussed them: the two boys got prizes for their hard work! The
talk which followed up with more information on each type is summarised in the article
overleaf for those who were not able attend this interesting meeting.

Friday, June 15th 2005
a Special invitation from the Friends of UWA Press
All those who were curious to know what the new University Club is like had a chance
to find out! The Friends of the Earth Science Museum were invited to join the Friends
of UWA Press in the Banquet Hall of the Club for their Annual Winter Dinner Function,
which comprised an interesting talk by the Head of the Perth International Arts Festival
about future directions for PIAF accompanied by a delicious and generous buffet
dinner. The Friends who attended enjoyed talking to other UWA ‘Friends’ groups at
their table in the splendid surroundings of the Club.
6        Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005

Some Common Ornamental Rocks and Minerals
By Jenny Bevan, Curator of the E de C Clarke Earth Science Museum at
Agate and onyx
Both these are forms of very fine-grained quartz (silicon dioxide, or
Formation of agate and onyx
Agate often forms in the empty spaces left by gas bubbles in lavas.
Watery solutions containing silica pass through the lavas and deposit
layers of silica around the walls of the cavity. Sometimes the last
deposit is a layer of quartz crystals.
                                         Some        agates       from
                                         Queensland (see left) form in
                                         rhyolite lavas after they have
                                         crystallised. The spherulitic
                                         crystal groups can have
                                         shrinkage spaces which
                                         then get filled by fine-grained layers and
                                         crystals of quartz.

                                          Onyx       is
formed in a similar way to agate. It is usually dark in
colour though it may have light bands in it. Natural
black onyx is rare, and most is produced by soaking
in sugar solution then carbonising: a similar method
was used by the Romans!
Both agate and onyx are very hard and cannot be
scratched by a steel point. They do not react with
acid. Generally the crystals of quartz are too small to
see, even with a lens.

Other fine-grained quartz ornamental stones are:
    • CORNELIAN (red);
    • BLOODSTONE (green with red patches);
    • MOSS AGATE (white with moss-like green mineral inclusions, or with black or brown
         dendrites of manganese oxides “mocha stone”);
    • CHRYSOPRASE (green because of nickel impurity),
    • TIGER-EYE and HAWKS-EYE (where fibrous blue crocidolite asbestos has been replaced
         by quartz. The asbestos breaks down, leaving yellow, brown or red iron oxides: tiger-eye,
         or retaining the original colour: hawks-eye)
    • JASPER (red, or in yellows and greens, sometimes with inclusions of green chlorite and
        Newsletter of the Friends of the C. Clarke Earth Science Museum:     August 2005        7

                                  What is the difference between cornelian and jasper?
                                  These stones are both made of fine-grained quartz, and can both
                                  be coloured red by iron oxides. However, cornelian is one of the
                                  CHALCEDONY group of quartz varieties, in which the tiny crystals
                                  of quartz are fibres, whereas JASPER and its varieties have minute,
                                  randomly-arranged, interlocking quartz crystals.
                                  The picture (right) shows the thin fibres of chalcedony in an agate,
                                  under the polarising microscope.

                                 Mexican Onyx (left)
                                 This is not true onyx. It is also often confused
                                 with alabaster. It is actually a kind of limestone
                                 (see below), with layers of calcium carbonate
                                 in bands resembling agate, often pale green
                                 or brownish.Try scratching a spot in an
inconspicuous place and dropping some acid (e.g. strong vinegar) on it. The
area will effervesce due to the release of carbon dioxide gas.

Marble and limestone
Both these are made largely from calcium carbonate, in the form of the mineral CALCITE. Some may
have the mineral DOLOMITE which is a carbonate of magnesium and calcium.

                                                 Formation of marble and limestone
                                                 Limestone is the SEDIMENTARY rock from which
                                                 marble is derived by recrystallisation during
                                                 METAMORPHISM. However, much limestone is sold
                                                 under the name “marble”.
                                                 If you can see fossils and other sedimentary grains,
                                                 then it is likely to be limestone.
                                                 If the grains seem to be a mass of interlocking pieces,
                                                 like a 3-D jigsaw, and there are veins or patches of
                                                 other material, it is probably marble.
                                                 Impurities in the original limestone can impart colour
                                                 to the marble, so that it may be brown, black, green
                                                 or pink: very pure limestone will give pure white
                                                 marble like that
                                                 used for statues.

                                                Note the coral in
                                                the top left-hand
                                                corner of this
Marble floor in Winthrop Hall, UWA              polished limestone
8        Newsletter of the Friends of the C. Clarke Earth Science Museum:    August 2005

Alabaster is made of the mineral GYPSUM, which is a hydrated calcium sulphate. Sometimes it is
banded. Gypsum does NOT effervesce when treated with acid. It is also very soft and should be
able to be scratched with a fingernail.
Formation of alabaster
Gypsum can be laid down as layers in salt lakes, or form as nodules and veins after deposition of
some sedimentary rocks.

Serpentine is soft and easily worked and polished.Most
serpentines are green in colour and may resemble
snakeskin. Where the olivine-rich rock had iron minerals,
red patches of iron oxides may be seen. Chrome oxides are
common and appear usually as black dots. The serpentine
from Tasmania (right) has developed the chromium-bearing
purple mineral, stichtite, around its black chromite grains.

Formation of serpentine
                                              This is another
                                              metamorphic rock. Originally it could have been an
                                              igneous rock with lots of the mineral OLIVINE (the same
                                              as the gem peridot) which is magnesium silicate with
                                              no water in its structure. The olivine-rich rocks can also
                                              be slabs of the Earth’s mantle which have been forced
                                              up into the crust during plate movements.
                                              When it was changed by heat and pressure, water was
                                              also involved and the new, fibrous, serpentine minerals
                                              (magnesium silicates chrysotile, antigorite and lizardite)
                                              which appeared contain water in their crystal structure.

Lapis lazuli
This spectacular rock is a mixture of the silicate minerals
LAZURITE, HAUYNITE and other blue minerals. It often contains
flecks of “gold” pyrite and white minerals such as calcite as well.
Why is lapis such a beautiful blue? It does not contain blue
coloured metal ions such as copper. The reason is that its crystal
structure contains sulphur, and the crystal lattice absorbs all light
except blue.
Formation of lapis lazuli
It forms as lenses and veins in contact metamorphosed marbles,
associated with pyrite.
        Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005     9

The best commercial lapis is mined in Afghanistan, which was also the source of this highly-prized
stone when used by the Egyptians many thousands of years ago. It is also now mined in Siberia
and in Chile, but material from these sources usually contains much white calcite.

Jade is an “umbrella” term which covers rocks of several
different kinds. True jade is one or other of two hard and
tough silicate minerals with colours usually ranging from white
through greens to black.
The mineral JADEITE (a pyroxene, a sodium-aluminium-
silicate) is granular and very hard. The pure mineral is white:
iron-bearing varieties are green, and emerald-green, and pink
or lavender varieties are known.
The fibrous mineral NEPHRITE (amphibole varieties in the
series tremolite, a white calcium-magnesium-silicate, to
actinolite, which contains iron and is dark green) is softer but
very tough. (image from )

Formation of jadeite jade
Jadeite, rarer than nephrite, is found only in metamorphic rocks. Laboratory experiments have
shown that high pressures but relatively low temperatures are needed for its formation. Such
environments are found near the margins of the continental crust such as the Alps, California,
Guatemala, and Japan. Because of its highpressure origin it is a relatively dense mineral, so seems
heavy for its size.
Jadeite is usually found as large, waterworn boulders, which may have a brownish weathered skin,
rather than being quarried. Burma is the main source of commercial jadeite.
Formation of nephrite jade
Nephrite jade is found usually in gneisses, which are metamorphic rocks.
In South Australia these gneisses are around 1800 million years old. In this case the amphibole
formed as lenses or veins because of a reaction between silica
solutions entering along fractures, and the host dolomite marble,
which contains magnesium.
In New Zealand, Canada and Taiwan, the nephrite forms as lenses
within or along the margins of serpentinised volcanic rocks which
would originally have been high in magnesium

Other ‘jade” - The term “Jade” is also used for some look-alikes.
    • AUSTRALIAN IMPERIAL JADE is chrysoprase, a green
         nickel-bearing chalcedony.
    • NEW JADE is bowenite, which is a translucent green
         serpentine used extensively in China. It is much harder
         than normal serpentine. The camel (right) is from China.
10       Newsletter of the Friends of the C. Clarke Earth Science Museum:    August 2005

     • PILBARA JADE is also a serpentine, which contains the green mineral chlorite as well.
     I have seen quite a few jade “fakes” including a clever one of coloured glass granules which
          had been sintered together to copy the granular nature of jadeite. Ordinary green glass
          can be made to look like high-quality nephrite.
This is a mixture of soft platy or fibrous minerals, mainlyTALC.
“Steatite” is the name given to massive talc, which is a hydrous
magnesium silicate.Soapstone is easy to carve and may be
greenish, brownish, grey, yellow or cream, or mixed in
appearance. Normally you can scratch talc with a fingernail,
but very compact varieties can be harder, such as the material
from Three Springs in WA.

                                   Formation of soapstone
                                   This        is     another
                                   metamorphic rock, which
                                   has resulted from heat and
                                   pressure,       and      the
                                   introduction of water, being
                                   applied to existing rocks
                                   and changing them.
                                   The       original     rock
                                   composition will determine the appearance of the resulting
                                   soapstone. Pure talc is colourless, and it is impurities which
                                   give it colour.
                                   Talc can form in schists (by metamorphism of magnesium-rich
                                   silicate rocks) or from dolomitic limestones and magnesites
                                   (which are mainly magnesium carbonates), especially where
they are in contact with a body of hot igneous material.

Malachite and other copper ores
                                           Green banded malachite is one of the most recognisable
                                           of the ornamental stones. It is a hydrated copper carbonate,
                                           and will respond by effervescing carbon dioxide if treated
                                           with acid. The banded shapes represent growth of the
                                           fibrous crystals in layers on a substrate.
                                           However, it often occurs mixed with other material which
                                           affects its properties. It also can occur mixed with a blue
                                           hydrated copper carbonate called AZURITE, or with a
                                           copper silicate of a deep turquoise colour called
                                           CHRYSOCOLLA. VERDITE is the name of a popular
        Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005   11

African stone used for carving which owes its
colour to copper minerals (see left for a rhino
carved in this stone).

Formation of malachite and other copper ores
Most form as secondary ores in the zone above
a mineral vein containing copper sulphide ores.
Percolating solutions have dissolved the
original ore, and in the aerated zone there is
plenty of dissolved oxygen and carbon dioxide
to allow the formation of carbonate minerals.
Zaire, Zambia and Russia have good deposits
of this kind, as does Australia.

Some simple tests to do at home
    •    What colour is it? Is it shiny or dull?
    •    Does it have a mixture of colours and textures?
    •    Can you see any crystals? Are there fibres or is it granular?
    •    Weigh it in your hand. Does it feel heavy? Compare its weight with something a
         similar size which you know. Is it magnetic?
    •    Using a large needle, and in an inconspicuous place, try and scratch it.
    •    If the scratch produces powder, what colour is the powder?
    •    Put a tiny drop of strong vinegar on the powder and see if it fizzes.
    •    If you have a spring balance, weigh it once in air then dunk it in water and see how
         the weight has changed. Divide the difference into the original weight for the Specific
         Gravity, then check in a mineral book.
    Another possibility is that the material is not a real mineral. If it is glass, you should be
          able to scratch it with a needle, and any chips will be broken off along curved
          surfaces (conchoidal fracture, which means it looks like a tiny shell)
    If it is a plastic or resin, then you should be able to scratch it easily with a needle.
          Some “carvings” are actually moulded from resin mixed with rock powder.Try heating
          the needle up in a flame and carefully put the point on the specimen in an
          inconspicuous place. SMELL!! if the smell is at all like burning plastic, then that is
          what you have! If the specimen is amber, however, you may smell a fragrant resin

    You can always bring in things for me to identify in the Museum!
I have plenty of reference books for you to look at, microscopes and so on I can use for
further testing, and a small accurate spring balance for measuring density.
12      Newsletter of the Friends of the C. Clarke Earth Science Museum:   August 2005

MUSEUM ROSTER: Contact Allan Hart 9360 5157 (business hours). He is
keen to get people for the next few months, so if you can, please help him by
offering to do a Sunday duty soon.

             Current roster
      Jul 31      Dennis Kelsall
      Aug 7       Allan Hart
      Aug 14      Jeff Bowen
      Aug 21      David Connolly
      Aug 28      Dianne Tompkins
      Sep 4       Jeff Bowen
      Sep 11      Danuta Stansall - to be confirmed
      Sep 18
      Sep 25      Steve Heath

Thanks so much, all of you, who have helped by being on the roster! Even if you don’t get
many visitors, it is important to be open when we promise we will be open, and who knows,
your visitor may spead the word to others (and even be the reason why a student does
Earth Science at U.W.A.!). Thanks also to those who organised their own “swaps”.
NB.If you are unable to be a “Friend” by doing a roster, please don’t forget that the
alternative is to give a donation towards newsletter expenses etc.: $15 is suggested.
Thanks very much to those who have donated this year!! Please make cheques pay-
able to: “UWA” (must have UWA on somewhere otherwise we cannot pay it in).
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

This field trip has finally been sorted out: because of the logistics we can
only take a small group, and it will be more expensive than our usual trips.
I think we may be fully booked, but please enquire from Mignonne Clarke
(9341 6746 or if you are very interested in case
there are any cancellations. The trip will run from 2nd Sept to 11th Sept.

STOP PRESS: another talk: see inside for other SCIENCE WEEK talks
“SymbioticA - The Art/Science Collaboration”               16th August 16:00-17:00
Free of charge: Agriculture Lecture Theatre, UWA Crawley Campus
  Gary Cass will present a talk describing his experiences working with artists and
  running the SymbioticA Biotech Art Workshops across Australia and internationally.

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