>> Friday, November 27, 2009

In a small-scale Cambodian gemstone mining site the predominate stones are quartz (rock and smoky) and topaz, but now we can add aquamarine to the menu of offerings.

Takeo Province, Cambodia, produces not just white and smoky topaz, but also aquamarine.

This week I spent a day at the base of the mountain talking to the gemstone cutters and sellers. And looking at their stones. Especially their gemstone rough (t'bong chau).

Most of these uncut crystals are very clear, though the larger they are, the more likely they are to be included. I looked at the inclusions with my 10X loupe and they exacty what was expected (GIA Gem Handbook).

All of the crystals in the photo above are Aquamarine, except for the fat stone near the center and on the top of the picture, that is Topaz, typical of what they find in the nearby stream beds. But the most telling point was that many of the uncut crystals are clearly symmetrical six-sided forms; Topaz simply does not grow that way, though some of the sellers persist in selling cut stones which are clearly too light in weight to be Topaz (by my admittedly subjective heft) , as Blue Topaz.
The fewer the inclusions, the smaller the piece of rough. The clearest stones -- and some of the crystals are flawless -- the thinner they are. There are two results: first, the thin small stones are cut into rectangular step-cuts (like an emerald, its 'cousin', might be) and second, the larger crystals with their large inclusions and breaks are carved into Khmer or Chinese Buddhas.
My whole plan to get two pieces of cut gemstone, one Topaz, the other a blue stone of the same carat weight foundered abruptly. (I wanted to see if the Topaz was smaller in volume).

The sellers do not own even the simplest of means to weigh their stones. They seem to estimate by eye the size of the stone and distinguish between them only on the basis of clarity, color if any, and type of stone, before they set their price. And my plan to buy some cut blue Aquamarine (and make tens of dollars)? That plan foundered also: any of stones available with significant color were visibly included. The brilliant, cut white (clear) Topaz is actually amazingly cheap; easy to see why it has been mistaken for diamonds. The sellers say that they are attracting a lot of visitors from Hanoi and from Ho Chi Minh City. They are well positioned to do that, the mountain is only half an hour from the border.

If you visit, remember: this is a culture that bargains. With the slightest pressure the sellers will drop 25% to 30% off of their marked price (just ask: "Som joh damlei bantic baan tee?" Can you please lower the price just a little?" And if that is a bit too much (my phonetization surely leaves much to be desired), just wave your hand, palm down, in a downward direction, pointing at the price, with a suitable modest and calm look on your face (Cambodians do not know how to react to anger or outrage or righteous indignation even if feigned (I don't know if they even do indignation, never seen it, or the signs are not accessible to foreigners :).

And at the end, say: "Awgun! (Thank you)" They will really appreciate the effort.

The fact is buying a gem from a poor Cambodian dealer is not just about getting a beautiful gemstone at a decent price, but also about walking away, thinking: what a nice lady, that was fun! :)


Headed Up The Mountain

The miner's wife that I had met on my previous visit to the top of Takeo's Topaz Mountain walked up and talked to us during our most recent visit. I had come back to the mountain two weeks later to determine once and for all if the blue stones that her husband and relatives and neighbors were digging up was in fact Aquamarine or not. (It was :)

She is such a lovely woman. I asked what she was carrying and she let me look in the straw basket that hangs off the front of the stick across her shoulder. Cooked rice in a blue plastic bag. Four small fresh fish, and a cup of coffee with milk and ice carefully placed in a clear plastic cup, covered with a plastic cap, but with a straw already inserted. An empty capped plastic jug hung off the stick between her and the coffee. On the back five kilograms of uncooked rice

She had an hour climb ahead of her, but was remarkably cheerful about things.

Like I said, a lovely woman.


Blue Topaz or Aquamarine?

>> Thursday, November 19, 2009

Once I got back down to the bottom of the mountain (hill), I went back to the faceted gemstone seller and asked for a piece of Blue Topaz rough (I will call it this, in deference to her :). She sold me a light blue-green stone for five dollars.

I took it back to Phnom Penh with me and did some digging in my books. Along the right had side of this post are some views of this piece of crystal. I don't have the ability to measure its specific gravity or reflective index (that would put to rest the question easily), but I can list some arguments in favor and against it being Aquamarine based on what I learned or could see.

1) Aquamarine is not ruled out by its color, nor is Topaz. Both stones occur naturally in low saturated blue-green colored gems. On color it could be either.

2) Topaz and Aquamarine are known to occur in the same geologic setting, so there would be nothing surprising about Aquamarine being found in a location where mostly Topaz had been found until now. In fact Aquamarine is often found with Rock Crystal and with Smoky Quartz as Topaz is here. Nothing to rule out Aquamarine here.

3) The gem sellers all say that this light blue stone is more difficult to cut than is Quartz (there never was a question of whether this was quartz, quartz does not occur naturally in blue). They could not say if faceting the stone was more difficult or easier than for Topaz. The ones who believe that this stone is naturally occuring blue Topaz say that cutting is the same as cutting Topaz itself. If it were Aquamarine, it would be harder than Quartz, but possibly as hard as Topaz. Nothing determinative here. Easy to see why the cutters cannot tell. (Mohs is a 10-point scale and a standard gemological standard for measuring relative hardness. Diamond is 10.0.)

Quartz (Mohs=7.0); Aquamarine (7.5-8.0); Topaz (8.0)

4) To my mostly untrained eye, the crystal form of the stone appears to be hexagonal. If I am right, that might in and of itself rule out the orthorhombic Topaz.

5) The piece of crystal rough that I bought has striations parrallel to the long axis of the crystal. Both Aquamarine and Topaz are known to display that, though most of the Topaz crystal rough I saw at this site (and bought on a previous visit)  had been worn and pitted by their travel to a final alluvial deposit. On the other hand, and contradictorily, a lot of the quartz was so finely formed and unmarked that the gemstone dealers talked about how it looked as if it had been hand cut and polished!

So, until I can get the specific gravity of this stone measured (Aquamarine: 2.63 - 2.91, Topaz: 3.5 - 3.6, strangely different sources vary in the numbers they provide), or measure the refractive index on a cut stone, I may be out of moves.

Unless. Unless I go back and look at two cut stones, one clear and clearly Topaz, and the other light blue, same cut, same carat weight, and see if the Topaz is smaller (higher specific gravity).

Or. Or, ask for two stones that look to be the same physical size (volume) and see if the blue one has a lower carat weight.

Yeah. Yeah, I think that is what I will do. And if it appears to be Aquamarine, I will buy me a couple of stones. You should see the international retail prices for good color stones. :)


At the Mine Head

>> Wednesday, November 18, 2009

In previous posts I have described Topaz Rough found in Takeo Province, faceted stone sellers at the base of the mountain where the stones are found, the climb up the mountain, and the view from the top. We also met an old miner who lives on the mountain, after meeting him we followed three miners to their work site, the mine shaft they have dug.

Well these mine 'shafts' are not that large. Once a promising location is found, a place thought likely to produce sellable stones, a group of men is organized and digging begins.

We went to one such location with three miners to see how the work went. It is very low tech, but that is a good thing. These rice farmers have a source of income that they otherwise would not. They are extracting at a pace that they can sustain.

Though no one knows when or if the mountain will play out (but good digs are more and more difficult to find and at greater and greater distances), but in the absence of major commercial interventions (which destroyed the Pailin ruby and sapphire mine sites, and made major in-roads among the zircon sites in Ratanakiri), these people are set to make money in small increments for many more years.

As they have for about ten years now.


Home on the Mountain

Most topaz miners 'commute' to and from their villages below. But a few live on the moutain-top, where small fruit orchards and vegetable gardens have been planted.

Our guide took us to the house of one man, who claimed to be more than seventy-years old. There we visited with him, took a look at his tools and the stones that he had recovered but rejected, unsellable quartz and topaz. Some of the discarded stones looked like rose quartz, another co-occuring mineral to aquamarine!



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