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Any ideas what this purple rock may be?

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I found this rock in the Clackamas River, Oregon. This river runs from Mt. Hood. It has some quartz in it but not much. I think it is metamorphic in nature. It is a nice purple with red rock. I am sure it is volcanic in origin. It is very heavy. I haven't tried any tests on it. Any ideas?

asked Aug 31, 2017 by trishberrong (250 points)

1 Answer

0 votes
Rhyolite maybe, volcanic rock.
answered Aug 31, 2017 by Weasel (58,930 points)
Thanks, will do research on rhyolite
Can't really be identified by a photo without any definitive visual cues.
Thank you. I did a lot of research on rhyolite and found a pic of one that was almost identical to the rock I have.

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