carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Jul 28, 2013 10:35:55 GMT -5
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Post by tandl on Jul 29, 2013 6:47:27 GMT -5
Although gabbro can be nearly all black appearing, it is not gabbro . You say sulfur smell and i see pyrite crystals and looks to be hematite -silvery black . i say a iron ore .
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jul 29, 2013 13:44:26 GMT -5
sulfur smell = sulfide of some sort. As Ted said, iron is the likely culprit.
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carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Jul 29, 2013 18:22:21 GMT -5
It leaves a white streak instead of red and is as hard as the concrete. I cut some off with the tile saw and the mud was greyish.
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Post by tandl on Jul 30, 2013 14:30:16 GMT -5
likely a limestone base, iron mineralization of limestone is common in varying degrees . Don`t take limestone as a bad word.there are many varieties ,some are lapidary grade which Yours appears to be
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jul 31, 2013 13:25:20 GMT -5
check for limestone with pool acid - bubbles galore! tandl you rock!
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