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Please help ID this rock! Some have fine quartz. Found near lava rock.

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asked Feb 17, 2014 by cassie c (160 points)

4 Answers

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This looks like chalcedony. Take a look at this page: http://www.minerals.net/mineral/chalcedony.aspx

Scroll down to the pictures and you'll notice a similarity. Where did you find these?

answered Feb 24, 2014 by hershel (52,800 points)


Thank you sooo very much! I have wondered & looked for the identity of this rock for years!! No one has ever been able to help me, but you! You are so right! How did you know? I have many nice pieces, some big & some small. I usually find pieces with fine or small Quartz crystals on them, like Quartz forms from it? Oh, I found them in Nevada. Thank you again!

Be Blessed, Cassie

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Glad I was able to help! - Hershel

answered Feb 25, 2014 by hershel (52,800 points)
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Chalcedony like this is commonly found in areas where there are volcanic rocks, from New Mexico, Colorado, Wyoming, Utah, Nevada, etc. It is a common form of cryptocrystalline quartz that forms from the breakdown of volcanic ash, which releases silica into warm waters. Changes in the environment can favor the production of crystalline quartz, which is why the two forms can often be found together.

answered Feb 25, 2014 by stonesinger (720 points)
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Thank you Stonesinger!

answered Feb 28, 2014 by cassie c (160 points)