Newsletter of the Friends of the E.de C. Clarke Earth Science Museum: August 2005 1 AUGUST NEWSLETTER 2005 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 E.de 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 E.de 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: http://www.ecu.edu.au/pa/rswa For more information: Margaret Broxx email@example.com Horizon: Ph 94868246 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ______________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _______________________ 4 Newsletter of the Friends of the E.de C. Clarke Earth Science Museum: August 2005 SCIENCE FAIRS!!! Some of our members enjoy the TripleS Science Fairs. These events Fairs 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 16th Street, Carine, parking off Osmaston Road. They are free to all, and Carine reasonably-priced food and drinks are available to purchase on the night: they run from 5.30pm to 8.30pm. ✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸✸ ✸✸✸✸✸✸✸✸✸✸✸✸✸ Good websites to visit: http://earth.google.com/index.html 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) http://www.doir.wa.gov.au/GSWA/index.asp Go to “Products and Services” and then choose “Online Publica- tions” 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). http://www.nhm.ac.uk/nature-online/earth/rock-minerals/ index.html for lots of exciting geological stuff, from pictures to talks. Newsletter of the Friends of the E.de 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 E.de 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 UWA Agate and onyx Both these are forms of very fine-grained quartz (silicon dioxide, or silica). 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 actinolite) Newsletter of the Friends of the E.de 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 slab. 8 Newsletter of the Friends of the E.de C. Clarke Earth Science Museum: August 2005 Alabaster 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 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 E.de 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 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 www.chinese-zodiac-symbols.com ) 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 E.de 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. Soapstone 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 E.de 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 odour. 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 E.de 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). ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ FIELD TRIP TO CARNARVON BASIN 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 firstname.lastname@example.org) 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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