thanks for showing the great stones, it looked like a real nice piece of rough and the translucence looks good also, you can soak these in water to get the stone re-hydrated and clear up some, Arizona is the worst(driest) place to keep these, the stuff found below the oxide layers has a tendency to turn opaque when they dry out. Here are some examples of Gem Silica I found in Arizona over the years:
Gem Silica is a Chalcedony so in essence it is very stable, but as many Chalcedonies go, heat and moisture can affect their appearance, I would not suggest heating this material!!! These pieces are from 4 different sources, the top left came from a leech field find outside the Baghdad mine area, this material was probably dug out of the oxide layer in the late 40's to early 50's and it is the most translucent piece I have, it is the same clarity no matter how moist it gets or how dry....the largest piece is super rare it was found in Manganese mine in Mexico and it will get somewhat opaque when in a zero humidity environment, the color actually improves though. I have had these stones for many years and they are super stable in all regards. Any Gem Silica can be kept dry, it should not craze or crack etc...there was some Opal found in Arizona of the same color and it would show tons of microscopic crazing when dry, this however, came from the dynamiting they did when mining it.
Joined: Thu May 20, 2010 2:21 am Posts: 32 Location: Chicago, Illinois
If it is affected by moisture I would consider the possibility that it is actually an opal. I have seen examples of both gem-silica chalcedonies and opals that look quite similar in terms of hue and 'gemminess.'
Actually I read the stability question from the angle of degradation, I don't believe that Gem Silica degrades physically when moist or dry, as with most Chalcedonies there is the porosity factor.....the same porosity that allows many Chalcedonies to be colored....all the Gem Silica that I have handled which changed in translucency when subjected to different moisture environments has returned to the state it was in before it was changed, meaning if in Arizona (Dry) and allowed to sit out for a week or so, the Gem Silica that shows a propensity for being opaque will be opaque in the dry environment, some will get transparent (to different degrees) when soaked in water.... None of the Gem Silica I have handled started cracking or crazing when changing the moisture environment......If one were to wear the stone in a high humidity environment (Seattle, Hawaii, Mississippi etc) it would probably be more inclined to be less opaque. Most of the stones that change the translucency appear to have come from the sulfide levels of the mines, most of the stones that are unaffected by moisture have come from the oxide layers....I am a hobbyist with a passion for the stone and unfortunately I can only speculate and deduct from my personal experiences, I'm sure there are many here that would be more adept at giving a true scientific analysis. I do recommend buying the stones DRY to see the true nature of the translucency!
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