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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Apr 29, 2014 21:12:20 GMT -5
I had some similar material from California. It was not silicified but rather a calcified mud formation and it is sedimentary pisolite rather than a volcanic orbicular rhyolte which is high in silica and much harder. Pisolite and oolite are separated only by the size of spherical bodies with pisolite ( fish egg stone) being the larger. There are also examples of agatized pisolite and oolite from several areas.....Mel
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on Apr 29, 2014 22:14:12 GMT -5
Awesome, thanks for the intel Mel...sounds like its time to slice a slab and take a peak. Cheers. Andy
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alan
starting to spend too much on rocks
Member since December 2013
Posts: 111
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Post by alan on May 1, 2014 14:34:43 GMT -5
rhyolite is volcanic and would not form spheres... Oolite forms in very specific carbonate environments like the Bahamas has now.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on May 1, 2014 14:47:08 GMT -5
Alan, there is a whole class of rhyolite ( orbicular rhyolite) that has included sphere formations. Leopardskin Jasper is just one example ( misnamed as it is a rhyolite) but there are lots of others especially in Mexico and the southwest. I collected several examples in the Eagle Pass Rio Grande gravels yesterday morning.....Mel
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Post by snowmom on May 12, 2014 6:40:13 GMT -5
fascinating stuff, don't forget to show us what it looks like when you cut it open. It looks like some color hidden in that first photo.
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on May 14, 2014 22:41:07 GMT -5
Well I am not sure about this one....check out the slab below. any positive IDs with the inwards exposed?
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Post by mohs on May 14, 2014 22:51:22 GMT -5
never seen anything like it fred Flintstones caviar?
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Post by jakesrocks on May 14, 2014 22:52:08 GMT -5
I think this would be similar to the material Mel is talking about. Don't have a location on this. It was inherited from a rocker friend who has passed on.
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Post by snowmom on May 15, 2014 6:20:11 GMT -5
that is awesome stuff... how hard is it? the gray makes me think limestone, but it doesn't look soft enough in the slab photo...
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Post by jakesrocks on May 15, 2014 8:14:32 GMT -5
The material I have is a silica replacement. Very hard. Wish I could have talked to my friend before he passed away, to get a location on it and much other material that was passed on to me.
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on May 15, 2014 9:59:30 GMT -5
jakesrocks I think this stuff is also a silica replacement. Going to cab a piece soon. Your sample is very similar, close up each orb seem to have a unique core. They look like maybe they were organisms or eggs of some kind... I think I recall the guy I got it from saying it was from Cali but not 100% on that.
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Post by jakesrocks on May 15, 2014 10:15:57 GMT -5
Can't recall the name of the mineral. Old timers is getting in the way. But the little spheres are a mineral that grows in spheres. If you look real close with a loupe, you can see what looks like tiny hairs radiating out from the center of a broken sphere.
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Post by snowmom on May 15, 2014 17:12:51 GMT -5
I saw photos of a kind of calcite which was little round things like that... going to go look for the link... I thought of this thread when I saw it... should have copied and pasted it right then. sigh.
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Post by snowmom on May 15, 2014 17:19:17 GMT -5
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Post by snowmom on May 15, 2014 17:27:41 GMT -5
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on May 15, 2014 18:39:50 GMT -5
snowmom you rock! Ooids from the Beck Springs Formation of Death Valley, California looks like a good match. Many thanks. Cheers.
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