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"arkansas" and "translucent" should get you started.

I bought one not too long ago. Tried it once, not successful-but want to save final analysis until i've worked with it a few more times.
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You'll has to send that to me for full inspection. :shrug:

(this is another reason to have a drawer full of "reject" projects a/k/a ROCK TESTERS!)

Or spoon test it against your other rocks, no...