Can someone identify this rock for me?

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Offline skeeter

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Can someone identify this rock for me?
« on: 18/09/2010 21:16:48 »
My son is a big rock nut and is always on the hunt for new ones to add to his collection.  My wife found this today out behind the house.  It is a nice light pop bottle green color in outdoor lighting and is about the size of a silver dollar.  Thanks




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Offline Bass

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Can someone identify this rock for me?
« Reply #1 on: 19/09/2010 18:17:52 »
White looks like quartz- conchoidal fracture is diagnostic.  If you can't scratch it with a pocketknife- then that confirms quartz.  Can't tell about the black material on the outside?
Old enough to have a grandson
Slow enough to study rocks
Thirsty enough to find a pub

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Offline Ophiolite

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Can someone identify this rock for me?
« Reply #2 on: 20/09/2010 09:54:29 »
The 'coating' ,material looks very much like pink feldspar (probably orthoclase), dark ferromagnesian mineral (probably biotite) and white quartz, which would make the main body - rightly identified as quartz by Bass - part of a quartz vein in a granite.
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