Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Apr 24, 2014 18:52:25 GMT -5
Hello everyone. Before I toss this into the garden, can someone tell me what this is? I'm almost guessing layered sedimentary stone. AKA half of a hardened sandball? Found San Pablo Bay area. East Bay Area, California.
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Post by jakesrocks on Apr 24, 2014 19:07:13 GMT -5
Before tossing it in the garden, check the hardness. You might have a surprise there.
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Apr 24, 2014 20:17:29 GMT -5
Thank you for the info. I don't have a hardness kit, but...I used steel on it (expecting to make a powdery mess) and it left steel marks on it. Difficult to tell from the picture, but the white streaks are the steel marks. It feels pretty dense as well. Any ideas? I'm curious now.
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carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Apr 29, 2014 19:54:35 GMT -5
It's folded and layered like some flints. I've picked some up where the space between layers was eroded kind of like yours is. When in doubt, whip the saw out!
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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 21:01:49 GMT -5
Yup, we have similar flint/chert all over the ranch here in Texas. That is sedimentary liesegang banding. The uneven erosion occurs because different layers have slightly different hardness....Mel
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Apr 29, 2014 23:30:21 GMT -5
I guess we have a lot of chert/flint out here...i'm use to seeing the green stuff though.
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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 30, 2014 7:57:37 GMT -5
Yeah, I'm an East Bay kid myself ( Oakland and Hayward). That entire coastline is full of Franciscan formation chert. Chert comes in all colors. Even the Morgan Hill Poppy is a form of Franciscan chert....Mel
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Apr 30, 2014 13:00:20 GMT -5
Sabre52: Ah, ALCO. Quick question, I live in Central Contra Costa County. Are there any areas close by, where I can find pet. wood? The only problem for me is identifying it. (Petrified forest...pretty easy. Small pieces...not so much LOL) Henry
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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 30, 2014 19:43:42 GMT -5
Henry: I believe I remember pet wood up near Calistoga north of SF Bay. I found a little when I was a kid in the Russian River gravels. Also some out around Antioch and east of Mt. Hamilton in Del Puerto Canyon. None I ever found way back when was of any real interest, just old brown/black wood and often not real well agatized. Here in Texas, we have so much brown black pet wood along the roads down George West way you can stumble over it and break something if you're not careful....Mel
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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 14:31:30 GMT -5
Looks like a stromatolite fragment... Could be calcified or silicified depending on groundwater and burial conditions
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