pretoria gem and mineral club · blue remains the most sought after colour of sapphire. a “star...

Pretoria Gem and Mineral ClubAffiliated to the Federation of Southern African

Gem and Mineralogical Societies

September 2009 Pretoria Rockhound Digest Pretoria Gem and Mineral Club Clubhouse: P.O. Box 36 888 No. 29, 26th Street, Menlo Park, Pretoria Menlo Park 0102 Tel. 012 – 460 1494 (only Sat. 11:00 – 15:00) South Africa website: www.fosagams.co.za/pgmc Chairman: Lex Krabbendam, 083 449 6812 Treasurer: Dave de Villiers 083 337 1541 [email protected] [email protected]

Secretary: Di de Villiers 082 562 8983 Vice-Chairman : Dieter Heinichen 012-991 5839 [email protected] [email protected] Editor : Heidi Naudé 072 923 2180 [email protected]

Programme Highlights for September 2009

*** Reminder: Educational Outing Tswaing Crater, Pretoria 30 August

*** Mineral Meeting – Best self-collected Specimen followed by Open Day: Swop & Sell & Social 5 September

*** Monthly Club Meeting 12 September

*** Educational Outing: Museum Africa, Johannesburg 20 September *** FOSAGAMS Outing – Griqualand West 24 – 27 September

A very warm welcome to the following new members who joined recently:

Rae White

May your association with the Club be enjoyable, long and productive.

Please Note:

1. There will be no Monthly Programme Meeting in September.

2. The Educational Outing to the Roodeplaat Botanical Garden has been cancelled.

3. At the time of going to press the date and details of the Silversmithing Course for September were not yet finalized; please enquire with Bernard Strydom at 078 187 3267.

http://www.fosagams.co.za/pgmc

mailto:[email protected]


PGMC Programme for September 2009: (as at 21.08.2009)

Date Event Time Contact Details

3 Sept Silversmithing Workshop open 19:00 – 21:00 Bernard Strydom, 078 187 3267

5 Sept Monthly Mineral Meeting – “Best self-collected specimen”

“Open Day”, Swop & Sell and Social – all dealers and non-club members welcome

Lapidary / Silversmithing workshops open

12:00 - 13:00 13:00 – 15:00

11:00 – 15:00

Piet Reitz, 012 – 998 5452

Lex Krabbendam, 083 449 6812


12 Sept Lapidary and Silversmithing Workshop open

Monthly Club Meeting

Committee Meeting

11:00 – 13:30

14:00 – 14:45

15:00 – 17:00

Note – short shift !




19 Sept Lapidary and Silversmithing Workshops open 11:00 – 15:00

20 Sept Educational Outing: Geology Section – Museum Africa, Johannesburg

To be confirmed

Horst Windisch, 012 – 807 7116

24 – 27 Sept

FOSAGAMS Outing – Griqualand-West

Douw Steyn, 083 260 7416 [email protected]

26 Sept. Lapidary and Silversmithing Workshops open 11:00 – 15:00

Cabochon classes on Saturdays – by appointment only Linda Stone, 082 598 9117 (after 14:00)

Faceting classes on Saturdays – by appointment only Phillip Alp, 014-574 3488 or 014-571 2159

Pretoria Gem and Mineral Support Group – Ken Treolar www.facebook.com

A maiden born when autumn leaves are rustling in September’s breeze, a Sapphire on her brow should bind; to bring her joy and peace of mind. Gregorian Birthstone Poem

Source: Wikipedia Zodiac Stones

Sapphire - Birthstone of September (amongst others)

Sapphire refers to the gem variety of the mineral corundum, an aluminium oxide, when it is a colour other than red, in which case the gem would be a ruby. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple or greenish colour. Pink-orange corundum is also Sapphire but is called Padparadscha. Blue remains the most sought after colour of Sapphire.

A “star sapphire” exhibits a star-like phenomenon known as asterism. They contain intersecting needle-like inclusions that cause the appearance of a six-rayed star when viewed with a single overhead light source.

Sapphires, with a hardness of 9 (Moh’s scale) are also used in infrared optical components, watch crystals, high durability windows, and wafers for the deposition of semiconductors.

Heidi Naudé

http://www.facebook.com/

1. Newsletter Distribution / Membership Status

Any queries regarding newsletters not received, or address/email changes should be directed to the membership administrator, Heidi Naudé at [email protected] or tel. number 072 923 2180.

2. Duty Roster – August and September 2009

September 5 12 19 26

Open – 11:00 am Dieter Nick Karin Piet

Duty Team Dieter / Linda Nick / Tish Wolf / Karin Piet / Elize

Close – 15:00 pm Dieter Committee Karin Piet

October 3 10 17 24 31

Open – 11:00 am Heidi Fay ? ? Dieter

Duty Team Felix / Heidi Nico / Fay S.Marie/Jean Helmut / Anny Dieter / Linda

Close – 15:00 pm Heidi Committee ? ? Dieter

Tea/Coffee will only be served once; this will also be applicable on course days. Fridge sales and workshop material sales will stop at 14:30 pm to allow for sufficient time to reconcile/close the cash box.

3. Election of Committee Members 2010

Please note page 8 of this newsletter being the Nomination Form for the election of our 2010 Club Committee. The election will be held at the Annual General Meeting in October. Should you be unable to attend the AGM you can still submit your nomination form either by email, by fax or hand it in prior to the AGM at the club’s reception desk. Please ensure that any person nominated is informed accordingly and willing to serve on the Club Committee.

4. Personals

Thank You - the Committee would like to thank John Bruigom for his generous donation of R 1 045 to the club funds. Thank you John, we will put the money to good use.

Thank You - the Silversmithers would like to thank Pot Fernandes for his generous donation of new Melamine table tops for their work stations.

Thank Yous – go to Fay Pierides for taking on the task of identifying and labelling the specimens displayed in the mineral show case; and to Arina Venter, who regularly helps out with the tea/coffee duties, washing of dishes and keeping our dishcloths sparkling clean.

Thank Yous – also go to Piet and Elize Smith who visited our honorary member Rob Smith of African Gems and Minerals in Germiston, surprising him with a nice gift basket and lots of Get Well Wishes from the club members. Rob is recovering well from a recent hip replacement operation.

As a token of appreciation, Rob donated a beautiful Pyrite crystal specimen to the club. (Photo similar to specimen received, source: www.wikipedia.com)


1. Monthly Mineral Meeting, 05.09.2009

The next Mineral Meeting is scheduled for Saturday, 05.09.2009 from 12:00 – 13:00 at the clubhouse.

Piet Reitz has kindly agreed to “stand-in” for our mineral expert Horst Windisch, who will be on holiday. This will be a show and tell session of your best self-collected (not bought) specimens. Thus bring along a maximum of three samples and tell us when, where and how you found them.

2. Open Day – Swop & Sell, 05.09.2009

The Swop and Sell will follow after the above meeting at approx. 13:00 as usual. Please invite your friends and family to join us at the clubhouse.

3. Educational Outing – 20.09.2009 Geology Section – Museum Africa We are very excited to finally visit the exhibits at the Geology section of the Museum Africa in Johannesburg on a special guided tour.

Meeting place and time will be confirmed by Horst Windisch, 012 – 807 7116 once you confirm your attendance.

4. FOSAGAMS Outing – 24. - 27.09.2009

Griqualand West

Have you booked your places for the forthcoming trip to the Griqualand West region? Douw Steyn will be our outing leader and Kosie Smit will be our host for the weekend. We will search for various types of Jasper and Tiger’s Eye.

Details of the trip have been published earlier in August, however if you need them again please do no hesitate to contact Douw via email ([email protected]) or fetch a copy from the notice-board at the clubhouse.

Red Jasper (photo: www.wikipedia.com)


1. Monthly Programme, 11.07.2009 – Introduction to Gemmology

28 Gemmology enthusiasts enjoyed a very interesting talk by Kevin Hean on the broad subject Introduction to Gemmology. Kevin brought various samples of jewellery and gemstones, identified them and passed them around for all of us to admire. He explained some of the tools used to identify gemstones and explained how they worked. After elaborating on the various practices currently used to enhance or even change the appearance of gemstones, he asked for his samples back and went on to reveal the true identity of the pieces, i.e. the peridot gemstone was actually a tourmaline, the amber necklace was plastic, and the rose quartz bracelet was clear quartz enhanced by the pink string. This showed us all how easy it is to mislead people on this subject and that colour alone is not a good tool to identify gemstones. Thank you Kevin for your time and efforts to educate us on this interesting subject; we are eagerly awaiting your next class!

2. Monthly Outing, 19.07.2009 – Crocodile Lodge, Midrand

34 people met on this beautiful Sunday morning “armed” with crates, bags and buckets and ready for “rock-hunting” at the Crocodile Lodge in Midrand. The owner, Charlie Munchardt welcomed us and gave us a short briefing on the rules and prices of the material and off we went.

Rockhounds hard at work – photos courtesy of Elisabeth de Beer

The material on offer included Rose Quartz, Jasper, Sodalite, Aventurine (green & pink), Tiger’s Eye (golden & blue), Unakite, Ocean Jasper, Zululand Agates, Buddstone, various Crystals etc., etc. – this must come very close to rock heaven, pre-selected top quality material and all we had to do was decide which sizes and how many of them to take. Thank you to Charlie Munchardt for making this a wonderful day for all of us and thank you to Horst Windisch for organizing it.

3. Monthly Meeting, 08.08.2009 - Frogs

Harold Braack educated and entertained us with his presentation on Frogs. Can you believe that we have 120 different species of frogs in SA alone? Some work only night shift, others prefer their day shift activities. Each specimen has its own distinctive call and Harold is quite a master of imitating various “froggy” sounds. Like our rocks and minerals Frogs come in all shapes and sizes, from tiny micromounts (Cacosternum Striatum, ± 14 mm) to nice cabinets size (Bull Frog) and then the boulder size (Goliath Frog). Frogs are amphibians and inhabit the planet already for 370 Mio. years. Their biggest threat is loss of habitat through development and mining activities; even pest control creates a big problem as their main diet consists of insects. Thank you Harold for sharing this wonder of mother Nature and your beautiful photos with us.

“Rockhound-Frog” indigenous to Theresa Park!!!

1. Geelong Competition - Final Reminder

You have only a few days left (until 31.08.2009) to submit your entries for the International Geelong Competition 2009 to Fay Pierides. The rules and regulations, entry forms and any other details regarding this competition are available on request from her ([email protected]).

2. South African Gemstone Stamps

A series of South African Gemstone Stamps has been issued by the Post Office. The four stamps picturing Sugilite, Garnet, Jasper and Rhodochrosite are not in the usual rectangular form but rather diamond shaped. Information on how to obtain them directly from the Philatelic Services of the SA Post Office is available from Horst Windisch. Pictures of the stamps will be shown in the next issue of the SA Lapidary Magazine.

3. Extract from the ColoredStone GemMail Highlights, April 2009

TRUE BLUES: Chris Smith’s Amazing Adventures with Tanzanite

Chris Smith developed a proprietary cobalt remover to clean coated tanzanite.

Photo by Fred Kahn & Sun Joo Chung.

A year ago, there wasn’t much new to be said about tanzanite, the oven-blued zoisite found only in its namesake country of Tanzania. Known to be benignly heated from brown to blue since its discovery in the mid-1960s, tanzanite was one of the gem world’s safer, most worry-free precious stones. Then, last summer, this gem suffered its first major gemmological scandal. Dealers started seeing lots of melee and calibrated goods with exceptional colour rarely seen in smaller sizes—as well as larger single stones with remarkably uniform colour. Working with goods submitted by dealers, American Gemmological Laboratories and AGTA’s Gem Testing Centre jointly discovered that some stones were being coated with cobalt to give them their stellar colour. Once detected, the labs quickly devised a regimen of easy tests to ferret out suspect goods. Although these labs and others were able to get the information into the trade quickly, random or batch testing of tanzanite did not fully alleviate the problem, especially with smaller, calibrated goods. As a result, Chris Smith at AGL developed a chemical bath which completely eliminated the coating without harming the underlying tanzanite. “I felt that the industry needed a more practical method for dealing with the stock already in the possession of wholesalers, manufacturers and retailers,” he recalls. “Many in the trade were concerned that they might already have coated tanzanite in their stocks and they did not want to inadvertently sell coated material.” The tanzanite bath allowed stones to be submersed and come out with a clean bill of health.

Some tanzanites are partially blued by nature. Photograph by Fred Kahn and

Sun Joo Chung.

In conversation with the Tanzanite Foundation and industry organizations, it was decided to withhold the cobalt remover’s formula. That forced Smith to occasionally strip coatings as a favour for customers of AGL (which, by the way, Smith has just announced he is planning to acquire from its former owner since 2006, Collector’s Universe). “I developed the bath as a way to make sure tanzanites were coating-free and thus re-establish confidence in one of our industry’s most popular coloured stones,” Smith says. “Otherwise, trades people would have had to spend considerable time and money to batch or randomly testing materials.”


Most tanzanites come from the ground as beer-bottle brown roughs.

Photograph by Fred Kahn & Sun Joo Chung.

A few zoisites are mined already blued—and in no need of heating.

Photograph by Fred Kahn and Sun Joo Chung

Blued By Nature

After spending months studying tanzanite, Smith decided last summer to visit the Merelani hills which are the only known deposit for this gem. “It was just a courtesy and curiosity call,” he says. “I wanted to learn more about the mining and production of tanzanite. And the best way to do so was by first-hand observation.”

Because every tanzanite that is mined is sent for heating, it is assumed that all of these zoisites need oven time to be baked to this gem’s distinctive violet-blue. But during a visit to TanzaniteOne, the De Beers-like mining and marketing organization for most of the world’s tanzanite, Smith found that a significant number of stones had already been blued in the ground—hence treating wasn’t necessary in all cases. “I was quite surprised to see a number of stones were coming from the ground with a natural-blue colour. So I started a project to determine a means of identifying natural-colour tanzanite. As part of this study I found there were three kinds of stones being mined,” he explains. “The first and by far the most predominant type are stones with a beer bottle-brown that need heating to be converted to blue; the second type have been partially annealed and display an overall blue appearance but still show brown in one direction. A third type has been fully annealed naturally and shows a complete blue coloration.” Does this mean that there could be what Smith calls “a new niche market” for natural-colour, as opposed to heated, tanzanite—similar to that for sapphire? Smith believes so, but is quick to say that applications of his findings are better left to marketers than gemmologists. Smith plans to soon publish the findings of his tanzanite study in a leading gemmological journal.

Mine-run zoisite shows that some tanzanites are blued by nature not by man. Photograph by Christopher P. Smith.

Pretoria Gem & Mineral Club Affiliated to the Federation of Southern African Gem and

Mineralogical Societies

Nominations PGMC Committee 2010

Members are invited to forward nominations for the new PGMC Committee in 2010. The elections will take place at the Annual General Meeting, scheduled for Saturday, 10th October 2009 at 14:00. Members unable to attend the AGM can still forward a nomination form to ensure their vote will count. Nomination forms sent via email ([email protected]) or via fax (012) 250 2709 must reach Heidi Naudé by 9th October 2009 before 13:00 pm.

Nomination forms may also be handed in at the Club until 10th October 2009, before 14:00 pm. Please note that the person you nominate must give consent for you to do so and must be willing to stand for election. Fill in the name of the persons nominated in the space provided and sign at the bottom.

Current Committee Members:

Designation Name Availability My 2010 Nominations

Chairman Lex Krabbendam Yes

Vice Chariman Dieter Heinichen Yes

Treasurer Dave de Villiers Yes

Secretary Di de Villiers Yes

Additional Piet & Elize Smith Yes

Additional Linda Stone Yes

Additional Karin Mayerl Yes

Additional Theo Peters Yes

Additional Wolf Windisch Yes

Additional John Bruigom No

Nomination submitted by: Date: Signature: ____________________________________________________________________________________


pretoria gem and mineral club · blue remains the most sought after colour of sapphire. a “star...

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