Deceember 15-17: SAN DIEGO, CALIFORNIA: Wholesale and retail show; Gem Faire Inc, Scottish Rite Center; Fri. 12-6, Sat. 10-6, Sun. 10-5;
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 Post subject: Bruce Bridges on Tsavorite
PostPosted: Tue Feb 23, 2016 1:30 am 
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Posts: 207
Location: Bangkok
Golden Gate Chapter
invites you to attend...
The History of Tsavorite and the Scorpion Mine
Presented by
Bruce Bridges

Thursday, Feb. 25
Bruce Bridges, son of the legendary geologist Campbell Bridges, will give a presentation and first-hand account of the history of tsavorite and the adventure-filled life of his father.

Campbell Bridges, renowned for his discovery of tsavorite, lead successful, if often perilous, hunts for some of the world's rarest gemstones in the uninhabited bush of East Africa. His buccaneering life featured frequent brushes with snakes and scorpions, big cats and buffalo. Bruce will share the story of his father's discovery of tsavorite in the Tanzanian bush in 1967 and how he came to be the first to bring tanzinte to the U.S. for identification. Campbell Bridges was also Tiffany and Co.'s consultant geologist on tanzanite.

In addition, Bruce Bridges will discuss the evolution and development of the famed Scorpion mining industry over the past five decades, up to and including the present day mining landscape in Kenya.
All are welcome to attend this event, whether you're a GIA alumnus, student, industry associate, hobbyist or guest. Please share this invitation with any others you may feel would be interested.
Event Details:
Date: Thursday, Feb. 25

Time: 7 p.m.

Cost: $25 Per person - Prepay by check only; credit cards and Paypal cannot be
accepted. Cash and/or checks will be accepted at the door.

Location: Hotel Rex Directions
562 Sutter St. (between Mason and Powell Street)
San Francisco, CA 94102
*Food and drink available at the bar may be brought into the lecture room.

To RSVP: Please RSVP to sfgiaalumni@gmail.com by Monday, Feb. 22

Send your check to:
SFGIAA
PO Box 5711
Walnut Creek, CA 94596

_________________
AJP, DG, working on GG + AG...
Faceting + Gemology Teacher at AIGS Bangkok
Gemology + Travel Writing + Photos -> http://www.justinkprim.com
The views expressed here are the author's opinions and do not necessarily reflect those of his employer.


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 Post subject: Re: Bruce Bridges on Tsavorite
PostPosted: Fri Feb 26, 2016 9:08 pm 
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A very interesting talk. I recommend it to everyone.


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 Post subject: Re: Bruce Bridges on Tsavorite
PostPosted: Sat Feb 27, 2016 12:04 am 
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Please, tell me some of the highlights. I'm still at home with a sore throat.


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 Post subject: Re: Bruce Bridges on Tsavorite
PostPosted: Sun Feb 28, 2016 12:20 am 
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He started with some marketing slides from some German seller (can't recall who), who showed how superior Tsavorite is to Emerald in all the things they measured. Toughness stood out to me.

He talked about color - lighter ones initially didn't sell at all so they put them aside. But he complained about others selling them as "Mint garnet", as he thought they should still be called Tsavorite.

He mentioned his Mom wanted to call it Campbellite (Have a Campbellite by Candle Light), but they decided to honor Kenya, and a nearby park by calling it Tsavorite. Some Germans preferred the name Tsavolite and still sometimes use it.

He talked about the history of finding tsavorite. His Dad first found it in 1961, when being chased by a local buffalo while looking for beryllium for the nuclear industry. They still have the samples he found. But he did not set up a mine there (don't recall the country). Next he found it in Tanzania, but the mines were nationalized (stolen). Then he found it again in Kenya where the mine currently is. Shortly before finding it in Tanzania (in 1965?), he brought some tanzanite to the US for identification. It had been sold to him as sapphire, but being trichroic, he thought it was zoisite. So he came to Crown in Shield's GIA lab to have it analyzed. (He was right of course). They suggested visiting the head of Tiffany's and showing it to him. He was interested if there was volume, so he hired Campbell Bridges as their tanzanite advisor and sent him on to the natural history museum, where his samples were bought. He went back to Tanzania, found sufficient volume for Tiffany, so Tiffany began to buy and promote it.
A few months later, when he found tsavorite, he already had the connections he needed with Tiffany. Tiffany didn't think that "green grossular garnet" would be a big seller, so they asked him for a new name, and tsavorite is what he came up with.

The mine is situated in a folded layer of rock. At the tops and bottoms of the folds there is a plasticly deformed rock showing boudinage which means sausage-age in French - like linked sausages, the layer separates as it is squeezed,and in the voids in between hydrothermal deposition, high temp and pressure form first tanzanite and then tsavorite. The higher temp and pressure keeps the tanzanite from surviving in gem quality. The sausages themselves vary from 4 cm to 3 meters in length.

Their mine consists of two tunnels. Tunnels are used to avoid having to remove large amounts of rock, causing debris mounds, and to make things easier. The debris is scattered along a large airfield, so it isn't noticeable. The tunnel follows both the top and bottom of a fold, thus giving them two potential pockets of tsavorite to find, as they pass through the sausage rock. They can tell they are getting close with indicator rocks of calcite and pyrite, as well as scapolite. When that happens they have very experienced miners slowly break out the tsavorite. It looks very much like a volcanic peridot "bomb". crystal faces are very rare. Once they have these pieces, they tumble them, which breaks the individual facetable parts apart (mostly), and then this is finished by cobbing non-tsavorite host rock off the tsavorite with clippers and splitting along fault lines, so that the final pieces are clean, and closer to pre-forms. Then they are graded, and anything above .50 carats is cut in house. Their original cutters were trained in Idar Oberstein, and came back and trained the locals.

Their employees have full health coverage, and only one accident in the entire time of mining - someone fell off a truck and broke their arm. This is due to their planning on water management, their 9 foot ceilings, and their care in supporting the rock in the ceiling, and their electrifying the mines, which only go back around 300 meters so far.

He spoke about the attack and murder of his father in some detail - I won't record that here, as I am sure you are all aware of it, and it made me very mad. While the trial was going on, they closed their mine (5 years) but continued full pay and benefits to their miners.
One thing resulting from the folk trying to murder the miners and take over the mines was that there is now some trade in "blood tsavorite", as some of the tsavorite being sold comes from mines that have been taken over. All stones they cut over 3 carats nwo are being laser etched with Campbell Bridges' signature, a serial number and the mine it came from.

He told some interesting stories of other explorations his dad and he did - they have both golden and chrome tourmaline in their mine as well as some tanzanite (not directly with the tsavorite.) He said their tanzanite is more intense than usual and good for melee. The biggest tanzanite they had found was about 10 carats.

They recently re-opened their mine (about a year ago) and started getting tsavorite out in Sept of 2015.

Hope that helps, Barbara - I wasn't taking notes, so this is all straight from memory.


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 Post subject: Re: Bruce Bridges on Tsavorite
PostPosted: Sun Feb 28, 2016 10:39 am 
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Thanks for the summary! I wish I could have been there. Bruce and his family are wonderful, and deserve credit for their commitment to safe mining and their support of the local miners.

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Lisa Elser, G.G.
http://www.lisaelser.com


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 Post subject: Re: Bruce Bridges on Tsavorite
PostPosted: Sun Feb 28, 2016 1:07 pm 
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Excellent! Excellent! Thanks a million.


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