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Post by Peruano on Feb 21, 2013 11:05:51 GMT -5
I'm not sure whether Devil's toenails category is a generic term or specific to a particular type of fossil and matrix/locale. This photo shows the knub, and two mirror slices of a beach rock from Guaymas/San Carlos area, that I initially presumed to include fossilized shells in a silica matrix. On the basis of input received below I'm tending to accepting rhyolite as a better id for at least the ones that I have cut so far. I'll add slabs of the others when the are cut. This stuff is hard. I have been tumbling some of it now for 3 days (vibe) and it is holding up well. This is one yet to be cut but shows the constituent critters. This one is less attactive but with more crystals showing. This one is the size of a grapefruit and about half of the mass is agatized. I realize I'm casting a broad range of specimens under the same name. Do I error. Saw / Slab work will come. Tom
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,687
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Post by Fossilman on Feb 21, 2013 11:20:20 GMT -5
Never seen devils toenails(oysters) in a red format before-thats cool!!!!
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Post by tandl on Feb 21, 2013 11:33:30 GMT -5
very cool
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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 Feb 21, 2013 17:54:45 GMT -5
Nope, don't think those are even fossils. Looks more like rhyolite similar to turkey tail or mushroom rhyolite...Mel
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Post by Pat on Feb 21, 2013 17:58:03 GMT -5
Toenails or mushrooms, it's an attractive rock.
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Post by Peruano on Feb 21, 2013 18:52:14 GMT -5
Thought I should add a few of the slices from today. The red matrix is quite hard and is the same that occurs in conjunction with the beach agates that I collect from the same locality in San Carlos, Sonora. Tom
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Post by Peruano on Feb 21, 2013 21:37:25 GMT -5
Mel, I was waiting for someone to say Rhyolite, and I agree that the one with the round figures does look a lot like rhyolite but its 1. harder than I would expect; 2. a red versus grey or brown matrix. and 3. Some of the other stones are distinct and even more likely to be fossils versus rhyolite. So in summary, some of these may be rhyolite and some a matrix containing marine fossils. Lets see what some of the others look like when cut. I have no vested interest in being right or wrong. Thanks for the input. Tom
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True Grit
noticing nice landscape pebbles
Member since January 2013
Posts: 76
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Post by True Grit on Feb 22, 2013 10:37:29 GMT -5
Ohh, my head. I never know there was a stone by that name let alone one that looks that cool. I'm new to this again... So I'm still learning
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rockingthenorth
fully equipped rock polisher
Member since January 2012
Posts: 1,637
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Post by rockingthenorth on Feb 22, 2013 10:55:19 GMT -5
I was thinking mushroom rhyolite too. It does have agatized parts in the last few pics. but the first one looks like mushroom to me. but I am no expert. you will have to see what every one thinks. Mel does know his rocks though.
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Post by Hard Rock Cafe on Feb 22, 2013 13:10:03 GMT -5
I was also thinking rhyolite. Devil's Toenails have a very distinctive shape.
Regardless, very nice pieces!
Chuck
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Post by frane on Feb 24, 2013 19:23:08 GMT -5
That looks like mushroom rhyolite to me. It can be agatized in areas and quite hard. It can look quite different if sliced at a different angle as well. Looks like some good material too! Fran
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Post by Peruano on Feb 25, 2013 18:32:37 GMT -5
Thanks everyone for the input. Mia culpa for hanging the wrong id on this material. I have yet to cut the two largest ones and am anxious to see what they disclose because they are more agatized (is that a verb), than the ones cut so far. Tom
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Post by deb193redux on Feb 25, 2013 20:37:51 GMT -5
I agree a rhyolite with small thundereggs embedded.
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jspencer
freely admits to licking rocks
Member since March 2011
Posts: 929
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Post by jspencer on Feb 25, 2013 22:58:01 GMT -5
In the picture where it has the more crystals showing I believe I spotted a tiny fossil sponge upon magnification. Many times the scars left from these is all that remains but never saw any orb shaped ones. They looked more like flowers. But I never cut one of these either so never saw past the crust on one. I may have to find out. I agree also that there is no Devils toenail shape to these.
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Post by Peruano on Feb 27, 2013 22:18:49 GMT -5
Just to finalize the rhyolite ID, I'll add a couple of photos of relevance. The large rock with the crystals apparent definitely came out as a rhyolite (golden ?) Its tiny (the size of my littlest fingernail) but seems to reflect the conclusive nature of rhyolite (I must admit it looks better in the flesh than the photo). Too much glare from the sun? Sorry for the initial misidentification as devil's toenails. Thats the way we learn. Some of this stuff came out of the vibe tumbler today and it looks great. Tom
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Post by helens on Feb 28, 2013 3:07:21 GMT -5
How interesting! I thought they looked like mushrooms I had, so I looked up my pix and the colors are opposite!! I have whitish mushrooms in a red background, and you have red mushrooms in a whitish background...how interesting! (I bought these on Ebay)
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jamesp
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Member since October 2012
Posts: 36,179
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Post by jamesp on Feb 28, 2013 20:04:21 GMT -5
That is from another world.amazing
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