• Register

Information for users from the old Q&A site
If you have an account from our old Q&A site, your account was transferred over, but you need to reset your password and confirm your email address.
Reset Password here
Confirm Email here

2,234 questions

3,904 answers


106,331 users

Hard brown rock with blue and white crystals, 30% cratered with small clear crystals, what is it?

0 votes

10"x8" 5lbs

asked May 25, 2016 by MarkyD (600 points)
edited Jul 27, 2016 by MarkyD

1 Answer

+1 vote
Looks like there is silification in the close-up, which would indicate the presence of chalcedony or agate. Can you please provide some more details?
answered Jul 24, 2016 by hershel (52,780 points)
I cut a small piece from it. The pics are  the first three The area cut is shiny, brown w/white. The Rock is very gemmy in sunlight.
White and blue is probably chalcedony. Chalcedony and agate are identical, chemically, both are silicates. The formation is different. My guess is chalcedony in some kind of matrix
I cut a little bit out of it. You can see the brown, some small pockets with small crystals. Also you can see how shinny it is just with a cut, it is hard, maybe MOHs 7. I can send you that chip!
I think to get a good ID I should cut it in half. The little bit that I did cut is very shiny without any polishing so could be interesting. Thanks all!