The Crystal GazetteVol 52 # 07 July 2013 STONE OF THE MONTH Zircon

Important Notices• No General Meeting

• Management Committee Meeting: 8th August, 6pm, Room 428, 38 Gawler Place Adelaide

TERACASTDiamond Merchants

T 08 8223 1123F 08 8227 1050

Suite 403, 38 Gawler PlaceAdelaide SA 5000www.teracast.com.au

louise@teracast.com.auContact Louise

Important Contacts:

President: Sue Arthur, FGAA,Dip DT,Cert IV T&A, M 0422 609 989

Secretary: Sandra Pimlott, FGAA, Dip DT Ph 8223 2362Treasurer: Don Bennett B.E. FGAA Ph 8296 1666Education: Tanya Cerny FGAA, Dip DT M 0401 213 835

Lise Jensen FGAA, Dip DT M 0428 363 698

Page 3 Gem Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. Zircon forms in silicate melts with large proportions of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. Colorless specimens that show gem quality are a popular substitute for diamond and are also known as "Matura diamond".Properties Zircon is ubiquitous in the crust of Earth. It occurs in igneous rocks (as primary crystallization products), in metamorphic rocks and in sedimentary rocks (as detrital grains). Large zircon crystals are rare. Their average size in granite rocks is about 0.1–0.3 mm, but they can also grow to sizes of several centimeters, especially in pegmatites. Because of their uranium and thorium content, some zircons undergometamictization. Connected to internal radiation damage, these processes partially disrupt the crystal structure and partly explain the highly variable properties of zircon. As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes. Zircon occurs in many colors, including red, pink, brown, yellow, hazel, or black. It can also be colorless. The color of zircons can sometimes be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, or golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above the temperature about 350 °C.Occurrence Zircon is a common accessory to trace mineral constituent of mostgranite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircon is rare within mafic rocks and very rare within ultramafic rocks aside from a group of ultrapotassic intrusive rocks such as kimberlites, carbonatites, and lamprophyre, where zircon can occasionally be found as a trace mineral owing to the unusual magma genesis of these rocks. Zircon forms economic concentrations within heavy mineral sands ore deposits, within certain pegmatites, and within some rare alkaline volcanic rocks, for example the Toongi Trachyte, Dubbo, New South Wales Australia in association with the zirconium-hafnium minerals eudialyte and armstrongite. Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR (economic demonstrated resources) for the mineral.Radiometric dating Zircon has played an important role during the evolution of radiometric dating. Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%) and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like erosion, transport, even high-grade metamorphism, they contain a rich and varied record of geological processes. Currently, zircons are typically dated by uranium-lead (U-Pb), fission-track, and U+Th/He techniques. Zircons from Jack Hills in the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, have yielded U-Pb ages up to 4.404 billion years, interpreted to be the age of crystallization, making them the oldest minerals so far dated on Earth. In addition, the oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth. This interpretation is supported by additional trace element data, but is also the subject of debate.

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Jadeite and corundum provide clues to earth's earlier history For years geologists were puzzled by jadeite. They didn't make any sense, said George Harlow, a geologist at the American Museum of Natural History, speaking to the New York Times. He is a member of a research team that has been studying gemstones to learn more about the earth's history.Today it is believed that jade provides physical evidence of oceans buried underground. As ocean tectonic plates were pushed beneath continental tectonic plates, the extreme pressures that were created forced atoms into new molecular arrangements. One of these was the mixture of sodium, aluminum, silicon and oxygen that is better known as jadeite. Writing in the journal Earth and Planetary Science Letters, Dr. Harlow and his fellow researchers reported finding jade-bearing deposits at the bottom of the Caribbean Sea that are 30 million years older than the surrounding rock. This, they suggest, is what you would expect to see if jade-producing fluid rises up from sinking oceanic crust before it is joined by other materials from a sinking ocean plate. Sapphires, too, are geological story-tellers, and especially corundum from the Indian subcontinent. There, mountain ranges like the Himalayas were formed when two continental plates collided 50 million years ago.

As the Indian tectonic plate slid underneath the Asian tectonic plate, rocks was squeezed and heated, including shale, which was formed from sediments that washed off land. When crushed, the shale produced crystals of aluminum and oxygen, which eventually became sapphires. Some of those crystals, as they were pushed up toward the surface of the Earth, moved through rocks that are rich in chromium. The chromium atoms replaced the aluminum atoms, transforming the stones into red rubies. The geologists credit the plate tectonic activity, which took place about 500

million years ago, for answering the question why there aren't any jade stones or rubies from the first nearly four billion years of the planet's existence. Earth is more than 4.5 billion years old, give or take a decade or so.http://www.gemewizard.com/newsletters/view_article.php?id=212

Diamond Digging in GhanaAuthor: Russell Shor, GIA 6/13/2013Akwatia, Ghana, is a town built by diamonds. Rows of low, corrugated rooftops branch out from the old town center. On the outskirts, where the small-scale farms begin, an occasional mansion rises beside the highway. Some of these mansions are owned by the lucky ones—diggers who found a cache of large diamonds. Most belong to the concession holders who take a cut from the finds of the galamsey, the local name for artisanal diggers who work the river banks.A half century ago, Akwatia was one of the most productive diamond spots on the planet. Diamonds were discovered at the nearby Birim River in 1920, when the nation was a British colony called the Gold Coast. By the end of that decade, production neared a million carats yearly, doubling by 1935.The Birim River remained one of the world’s most productive sources through Ghana’s independence in 1957, until the late 1970s when the richest areas were mined out and the aging mining equipment was unable to efficiently process smaller, lower-quality stones. Today, that is most of what the artisanal diggers recover: Of the 301,000 carats mined and exported each year, the vast majority are darker stones smaller than 0.10 ct.In the late 1980s, the government allowed the small-scale miners to work areas along the 40-mile diamond-bearing stretch of the Birim River, an area unsuitable for mechanized mining. While some

miners have registered, in compliance with government requirements, about 75% have not.In 2012, an investor group announced a $100 million plan to revive mechanized mining at Birim River. Still, the government and investors have pledged to maintain concessions for the artisanal diggers who now sustain the economic life of the region.Artisanal miners work a deposit near Ghana's Birim River.

http://www.gia.edu/gia-news-research-diamonds-Ghana?utm_source=gianews&utm_medium=email&utm_campaign=2013-06-25

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Notes & RemindersNotes & Reminders

TO REGISTER for any GAA course PLEASE CONTACT:Education: Tanya Cerny FGAA,. M 0401 213 835 or

Lise Jensen FGAA M 0428 363 698 orSecretary Sandra Pimlott 8223 2362, sandrapimlott676@hotmail.com

2013 Courses –Commencing datesPlease note there has been a price increase in some courses.

1. Intro to Gemmology Aug, Nov- $295This basic course is designed for jewellers, hobbyists or for people traveling overseas.Gems and Gemmology provides students with an opportunity to assess whether they wish to pro-ceed with a range of more advanced short courses or the intensive two year Diploma in Gemmo-logy.

2. Intro to Antique Jewellery- 20 July-$275Presented by Ian Strout from Ottaways Jewellers and SilversmithsOne Day course Saturday from 10am to 4pm,Class numbers will be limited to 10 peopleCOURSE CONTENTSANTIQUE JEWELLERY - Identification - HallmarksAustralian Antique JewelleryAntique & Period Jewellery - Georgian & Victorian etc.Antique Sterling SilverAustralian – English – Continental

3. Gemmology Update- $2750*4. Retail Diamond Consultancy- TBA- $2955. Pearl & Bead threading- TBA- $245 M $265 NM

*Course offered depending on numbers enrollingNote :- Prices given are members prices- Non-members please contact Secretary for prices

General Meeting: No General MeetingGeneral Meeting: No General Meeting

ROOMS ATTENDANCE AND VOLUNTEERS- ChangeROOMS ATTENDANCE AND VOLUNTEERS- ChangeThe GAA lab is open to the public between 10am-2pm. As members, you are welcome to come in and use the instruments in the lab for free.

LIBRARY BOOKS-LIBRARY BOOKS- Would any members who have books on loan from the Library please return them as soon as possible to the rooms. Thanks, The Librarian

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Bargaining for Gems in ChanthaburiAuthor: Russell Shor, GIA 4/30/2013A middle-aged woman in a floral dress and sun visor zips open a plastic bag and spreads an array of polished rubies across a desk blotter, taking care to keep them in the sunlight, where the colors come through richer. Behind the desk, a bushy-bearded buyer combs through the parcel with his tweezers, setting aside a dozen stones in about as many seconds. The dealer punches a per-carat price into her calculator. The buyer types in a counteroffer, and the two silently bargain until a deal is struck.At the Chanthaburi gem market in southeastern Thailand, where buyer and seller often speak no common language, the calculator is a universal translator. Chanthaburi’s gem trade dates back centuries—accounts of mining and trading there began in the 15th century—and today its gem market remains one of the world’s largest and liveliest.Thailand is one of the world’s leading colored gemstone cutting and trading centers. It exported an estimated $650 million worth of gemstones during 2012—about half of that sapphire, according to the Gem and Jewelry Institute of Thailand. While most traders keep their export offices in Bangkok, the traditional center of the colored stone industry, the place where nearly all of the cutting is done, is Chanthaburi. This town of about 30,000 lies 150 miles southeast of Bangkok, near the old ruby and sapphire mining area of Pailin on the Cambodian border.The Chanthaburi gem market is a relatively quiet place during the week, with a few dozen dealer shops on narrow Si Chan Road offering loose gemstones, gold settings, and equipment, such as electronic scales, lighting, and loupes and tweezers. But the weekend is when the market truly comes alive, spilling into the neighboring streets and alleys. Beginning at 10 am Friday, hundreds of dealers from around the country and many parts of the world set up makeshift stands with scales, calculators and, of course, gems. Within 30 minutes, the streets are teeming with buyers, brokers, sellers and an occasional tourist. The trading continues until dusk. Unlike traditional markets, most of the people sitting at the tables and desks are buyers, not sellers.The center of the action is at the intersection of Si Chan Road and Thetsaban Road, where the streets serve as an impromptu gem exchange. Buyers will find a seat at a table, sometimes posting a sign listing their wants, and wait for brokers or dealers. Runners working with the dealers dash from table to table, taking orders, showing gems and carrying price offers back to their bosses. Some dealers hurry to intercept the buyers before they get to the tables so they don’t have to pay commission to the table owners.What’s for sale? Not surprisingly, a vast majority of the dealers were offering ruby and sapphire of all colors—some for as little as $2 or $3 per carat. Are treatments disclosed? The price is the disclosure, said one dealer who’d stopped by to show a parcel of ruby. Sellers also showed spinel, various colors of tourmaline, tsavorite and spessartite garnet, and even amethyst and citrine. Between the gem vendors and exchanges is a veritable smorgasbord of street food, with vendors offering noodles, barbecue chicken, mangoes and soup bowls.On the side streets behind the market are dozens of “burners,” operations that apply heat and other treatments to gemstones. Most of these have no sign out front but are well known to the local trade.Veteran dealers say the trading at the market is quieter than a decade ago. They blame Western governments’ sanctions on Myanmar and the general economic malaise in many key consuming markets. But the market has survived transitions before. Indeed, Chanthaburi’s gem trade has been rejuvenated to some degree by diffusion treatments that can turn unattractive (and unsellable) corundum into low-cost yellow sapphire. Because of this, at least 10 mine sites are now in operation near Khao Ploy Waen and Ban Ka Cha. Additionally, one site produces black star sapphire that is not treated.Despite the slower sales, dealers such as the woman in the floral dress believe Chanthaburi will always have a place in the world gem business, because the skills and the infrastructure vital to the industry are still

concentrated here.

A buyer checks a large parcel of blue sapphire in the open-air Chanthaburi market while the dealer holds the rest of the lot.

http://www.gia.edu/gia-news-research-Chathaburi-gem-market?utm_source=gianews&utm_medium=email&utm_campaign=2013-06-25

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Rose quartz set a price record for most valuable fine mineral specimen offered at auction

The La Madona Rosa, a specimen of rose quartz, set a price record on June 2 as the most valuable fine mineral specimen ever offered at auction, when it was bought for $662,500 at Heritage Auctions' more than $3.57 million Nature & Science sale in Dallas. It was part of the Hoppel Collection, which accounted for almost 85 percent of the total value of the auction. The La Madona Rosa is thought by many to be better than the celebrated Van Allen Belt rose quartz, which can be seen in the Smithsonian Institution in Washington, DC. Standing almost 40 centimeters tall, the La Madona Rosa towers over the 23-centimeter tall Van Allen Belt. The 2,000 piece Hoppel Collection is considered to be the most valuable fine minerals assortment ever offered at auction. Among the other items from the collection that were sold was a rarely-preserved gem-grade aquamarine crystal found in the early 1990s, which sold for $158,500. A rare world-class specimen of linarite also realized $158,500, set a record for the highest price paid for such a specimen of its kind. The auction featured a large specimen of rhodochrosite from the old Home Sweet Home Silver Mine in Colorado, which fetched $146,500; a gem-quality ammonite from the late Cretaceous era which realized $80,500 and a Brazilian tourmaline crystal standing 41 centimeters tall, which realized $68,500. A 25.5-centimeter tall specimen of pink kunzite also was picked up for $68,500. It actually was traced back to George F. Kunz, Tiffany & Co.'s vice president and chief mineralogist in the early 1900s, after whom kunzite is named, who gave piece to his Tiffany co-worker George Wild. Other notable gemstones that were sold included a 21.41-carat tanzanite gemstone which realized $30,000; a deep red 93.6-carat cuprite gem from Namibia, sold for $20,625; and a 237-carat fluorite gemstone, mined in New

Hampshire, which fetched $16,250.

The 40-centimeter tall The La Madona Rosa rose quartz.

http://www.gemewizard.com/newsletters/view_article.php?id=208

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New York legislature to consider rare gemstone as state's official mineral

The Herkimer diamond, a doubly terminated quartz crystal that is predominantly found in Herkimer County in New York, is the subject of a bill passed by the state senate in Albany, which declared it the official mineral of the State of New York. The bill will now go to the state assembly for final approval. "The Empire state has a proud tradition of recognizing and trumpeting the features that make it unique," noted Senator James Seward, R-Oneonta, in a release to the media. "Certainly, the Herkimer diamond is one of those rare treasures well deserving of 'official' statewide status." Interestingly, New York State already has an official gemstone. The wine red garnet officially received that title in 1969. But, to date, no official mineral has been designated. Doubly terminated gemstones, which are crystals with two naturally faceted ends, are rare, making

Herkimer diamonds popular with gem collectors. They grow with very little or no contact with their host rock, and score 7.5 on the Moh's hardness scale. New York State is not the only known source of doubly terminated quartz crystals. Similar stones have been found in Arizona, Afghanistan, Norway, Ukraine and China, but, because they were not sourced from Herkimer County, they cannot rightfully be called Herkimer diamonds.

A Herkimer diamond in its host rock. (Photo Credit: Marianne Kempf)

http://www.gemewizard.com/newsletters/view_article.php?id=214

Argyle celebrates underground mining launch with limited edition of pink diamond ingots

To celebrate the launch of underground mining operation at the Argyle diamond mine in Western Australia, Rio Tinto has announced the release of a limited edition of one-ounce gold ingots set with Argyle's distinctive products, pink diamonds. Created by the mint in Perth, 168 individually numbered ingots will be sold internationally. The

starting price is about $4,200. Seven pink diamonds are set in the 22-carat pink gold ingot, which also features the image of a boab tree on one side. The ingots can be ordered from the Perth Mint. The underground mining operation is expected to help extend the potential of the Argyle mine through 2020, boosting output about 20 million carats per year. Pink diamond make up only a tiny fraction of the production, but Argyle accounts for about 90 percent of the pinks produced worldwide.

Argyle's limited edition pink diamond ingots.

http://www.gemewizard.com/newsletters/view_article.php?id=213

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Crossword

Across1 An animal shell used as a biological gem, characterised by it keratin matrix and melanin pigments.4 A process used to synthesis a variety of gems, including emerald and ruby6 A type of Jade, belonging to the Amphibole family8 A copper silicate hydroxide, can come in star form, trigonal system. Usually emerald green to bluish green in colour9 A mineral inclusion that may be found in peridot

10 Cavity produced by gas bubbles in a molten rock mass, which when solidifies may be invaded by hydrothermal solutions. Amethyst is commonly found in these.11 The type of UV wave found at 254nmDown1 A calcium aluminium silicate hydroxide. Found in the orthorhombic system. In it’s more common state, is a brown colour, but when heat treated turns into a lovely blueish- purple state, for which it is famous for.2 A crystal system, where a≠b≠c, where a1, a2 and c are at 90°3 In a polariscope, the prism at the top, which is 90° to the polarizer.5 The term used to describe a low type zircon7 The type of cleavage seen in Amazonite8 Gems certain characteristic that a gem must possess. A gem must be …

Molly Addyman, Victor Gostin and the opalised plesiosaur20/06/2013 , 2:46 PM by Michaela Andreyev

Back in 1811 an Englishwoman found the fossilised remains of a plesiosaur. The world was amazed by an aquatic creature which had a Loch Ness like monster appearance. Skip forward a century and a half and Molly Addyman and her husband were fossicking for opal at Andamooka in the State's outback when they discovered an opalised bone from one of these remarkable creatures. Molly Addyman came into the 891

Studios to relive the find and ask (our) regular geologist Victor Gostin about the way opal is formed.Listen to the pod cast at http://blogs.abc.net.au/sa/2013/06/molly-addyman-victor-gostin-and-the-opalised-plesiosaur.html?

site=adelaide&program=adelaide_mornings9

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2013 GAA CalenderMonth General Meeting Other EventsJuly Fri 26th Gem 1 and Gem 2 Mid Year Exams

Introduction to Antique Jewellery

August Fri 23rd Intro to GemsSeptember Fri 27thOctober No General Meeting EOY ExamsNovember No General Meeting Intro to GemsDecember No General Meeting

Please note these dates may change. Watch this space for upcoming events and date changes.

Quiz NightDue to popular demand, the ever popular quiz night will be happening again. Watch this space for updates on time, date, location.So, sharpen those pencils put those thinking caps on.

Update from previous story:Petra's 25.5-carat rough blue diamond bought for $16.9 million A rough blue diamond weighing 25.5 carats that was extracted at the Cullinan mine in South Africa in April has been sold by the mine's owner, Petra Diamonds, for $16.9 million or $663,144 per carat. "The process was highly competitive in terms of bids received, due to the incredible rarity of a blue stone of such size and quality," according to Johan Dippenaar, CEO of Petra. "This result further serves to highlight the Cullinan mine's unique position as the world's most important source of blue diamonds." Among the blue diamonds mined at Cullinan over the past five years was a 26.6-carat rough stone that yielded a fancy vivid blue, internally flawless 7-carat polished diamond, which was sold at a

Sotheby's auction in May 2009 for $9.49 million, or $1.35 million per carat. Named the named the "Star of Josephine" by its new owner, it was at the time the highest price per carat for any gemstone sold at public auction. Cullinan, which previously was known as the Premier mine, was bought by a consortium led by Petra from De Beers in November 2007. Over its more than 100 years of production it has provided some of the largest and most illustrious diamonds discovered, including the 3,106.75-carat Cullinan Diamond, which was mined in 1905 and since has held the record as the largest rough diamond ever mined.

The 25.5-carat blue diamond, which was discovered at Petra's Cullinan mine in April.http://www.gemewizard.com/newsletters/view_article.php?id=206

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Pair of jadeite bangles sell in Hong Kong for $6.9 million

A pair of jadeite bangles has been sold in Hong Kong for a mouth-dropping $6.9 million. The buyer, who was unnamed, delivered his bid by telephone during the sale conducted by Tiancheng International Auctioneers on June 15. Unsurprisingly, the jadeite bangles were the most valuable items sold in the auction, which generated about $37 million in sales. About 79 percent of the items on offer by value were sold. The cylindrical jadeite bangles are about 5 centimeters in diameter and are of a highly-prized translucent bright green color. They were carved from the same piece of rough, which was sourced in Burma (Myanmar). "Their size is large and as they were carved from the same rough, it would have had to be very big so that there was enough material to carve two similar bangles," said Ellen Sin, director of Tiancheng's jewelry department, speaking to the British Daily Mail. "The two bangles have a fine texture and translucent with very few impurities, the most desired quality of jadeite. It is so rare to find a big rough with very fine quality texture. They are top quality and when they are carved from the same piece of rough they are invaluable jewels." Other highlights of the sale were three natural unheated Burmese ruby and diamond necklaces that sold for $3.2 million, $2.13 million and $680,000.

The $6.9 million pair of jadeite bangles. (Photo Credit: Tiancheng International Auctioneers)

http://www.gemewizard.com/newsletters/view_article.php?id=205

CrossWord CluesAcross1 Tortoise 4 Hydrothermal 6 Nephrite 8 Dioptase 9 Chromite 10 Geode 11 ShortDown1 Tanzanite 2 Orthorhombic 3 Analyser 5 Metemict 7 Incipient 8 Durable