Identity Help. Plasma Agate, or Gem Silica


Hi again, was wondering if anyone could help me differentiate between plasma agate and gem silica? Pretty sure this would be considered plasma agate as a whole rock, but wondered if the green translucent areas are gem silica, or is it just called agate?

Looks like Chrysoprase Scott, a form of cryptocrystalline silica. The apple green of the top photo is a strong match for it.


The correct gemological term would be chalcedony if your specimen is indeed microcrystalline quartz


HI there mr Jbergman, This looks like Gem-Silica to me.

If I’m understanding it right, chalcedony that is green would be chrysoprase, whereas the blue to blue-green form would be gem silica. Based on the green color of some of it, I’d call it chrysoprase. The color is nice where you have lit it, but it doesn’t look as translucent as the best chrysoprase. Still probably some nice cabs in there. -royjohn

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I’m thinking that it would have to be tested and that would more relay on chemical markers and factors and other makeup matter /chemical composition, but…! from what I can see from the pictures it looks to be gem-silica. however any answer without having handled and tested the materials is a speculative guess at best and somewhat hypothetical until proven to be as some guesses can be spot on and others way way off. So as I always say testing and close examination of chemical composition is super important it is very very difficult to tell from a picture or photograph what a gem is or was as some gems are different with in two chemical degrees and also with some of the very very convincing synthetics made today it has become super difficult to tell without further testing for other factors of non natural occurrences.

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Thanks again everyone! You’re all amazingly helpful and informative in this. I realized I didn’t include much info other than the pictures. The greenish gemmy layer here is quite soft, but harder than fingernail. The surrounding matrix is much tougher/harder. HCl definitely dulls both the matrix and the greenish material. Specific gravity will have to be done after I have someone separate the two materials.
This is another piece of what I believe is the same material with some slight differences, both are from nearly the exact same area.
The cut piece is another similar material from the same area. I think I’ll stop cutting these at this point though:)

Cryptocrystalline or microcrystalline quartz is called by a confusing variety of names, depending on color and the element responsible for that color. In most cases that element is iron present in one of two states: either Ferrous (green) or Ferric (red). Chrysoprase is different and colored by nickel.