nansaidh
spending too much on rocks
Jewelry artist, graphic designer, dog lover, car nut (etc.)
Member since August 2008
Posts: 311
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Post by nansaidh on Aug 18, 2008 20:39:33 GMT -5
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,463
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Post by Sabre52 on Aug 18, 2008 22:46:18 GMT -5
Yep looks like more Franciscan formation brecciated jasper. The last black and green one is a dead ringer for Boar Canyon jasper from the Parkfield area near Stone Canyon....Mel
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karenfh
fully equipped rock polisher
Member since November 2006
Posts: 1,495
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Post by karenfh on Aug 19, 2008 0:40:55 GMT -5
Not a clue, but wow! Thanks!
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nansaidh
spending too much on rocks
Jewelry artist, graphic designer, dog lover, car nut (etc.)
Member since August 2008
Posts: 311
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Post by nansaidh on Aug 19, 2008 10:56:18 GMT -5
Yep looks like more Franciscan formation brecciated jasper. The last black and green one is a dead ringer for Boar Canyon jasper from the Parkfield area near Stone Canyon....Mel Thank you oh God of Multiple Parallel Universes Full of Rocks and Apprentice to THE ONE! (you need to acronym-ize that to GMPUFRATO) ;D What would cause that brecciated jasper to be all pitted like that? Is it just the way it happened to form? Is the white and green area quartzite? Nancy
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,463
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Post by Sabre52 on Aug 19, 2008 15:18:31 GMT -5
Howdy Nancy, The pits are usually caused by softer spots of quartz or, oxides which are not fully replaced by silica. These soft spots weather faster so create pits in the stones. The green colors are usually due to iron, chromium or chlorite salt inclusions in the stones. Picture #6 does look like a quartzite which is a common metamorphic rock throughout California....Mel
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nansaidh
spending too much on rocks
Jewelry artist, graphic designer, dog lover, car nut (etc.)
Member since August 2008
Posts: 311
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Post by nansaidh on Aug 19, 2008 16:39:44 GMT -5
Howdy Nancy, The pits are usually caused by softer spots of quartz or, oxides which are not fully replaced by silica. These soft spots weather faster so create pits in the stones. The green colors are usually due to iron, chromium or chlorite salt inclusions in the stones. Picture #6 does look like a quartzite which is a common metamorphic rock throughout California....Mel Cool - thank you. I'm just learning about the rock types - hopefully I'll retain some of what I'm reading. lol Thank you again!! Nancy
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