Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Feb 14, 2013 9:50:49 GMT -5
Hello all, I found this piece at "Agate Beach", Bolinas, California (Marin County). This place is know for it's small-sized oil agates. I found this deeply pock marked piece (only one divot) and I am wondering what it is. It does have the bizarre white pattern and slight ares of translucency. Under the surface it looks rather grainy. Is this an agate mixture or some sort of chert? Thanks! Attachments:
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Tommy
Administrator
Member since January 2013
Posts: 12,684
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Post by Tommy on Feb 15, 2013 9:05:52 GMT -5
Henry since no-one else is chiming in - I still think it looks like a very large specimen of the oil agates we find there at Bolinas. Some of them that I've found have been nearly opaque - I picked up a bunch that actually turned out to be black. I had to weed those out when I got home by shining a flashlight through them - did you try that with the flashlight?
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Feb 15, 2013 9:47:12 GMT -5
Thanks for replying Tommy. Yes, I tried the flashlight test. Surface translucency with areas that actually shines through, but mostly opaque with a sandy, grainy under surface. Sorta' like, hollowing out a nugget of obsidian and put some sand in it. That's what it looks like.
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Tommy
Administrator
Member since January 2013
Posts: 12,684
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Post by Tommy on Feb 15, 2013 14:04:30 GMT -5
Yeah if your seeing any translucency at all then my vote is that its a heavily included oil agate. We found a lot of smaller ones in the same condition - very opaque almost to black and heavily included.
I love the white patterns though. Didn't see much of that in our batch.
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Post by helens on Feb 18, 2013 19:53:03 GMT -5
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Feb 20, 2013 23:16:17 GMT -5
Thanks Helen. I read somewhere that >95% of meteorites are rich in iron...ergo stick to magnets. No such luck
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Post by stephan on Mar 9, 2015 14:31:51 GMT -5
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