I've found some rock alot like that here in tx. I'm not sure what it is. I think it comes from a large shale deposit on the river because the colors are the same. I could be wrong . What type of formation is Rhoylite from?This is found in large tabs & boulders. Sometimes it is is so fine grained it is almost like novaculite, but it is hard to get it from the cortex. The cortex is about 3/4" thick on the fine stuff with the good material only about 5/8 thick.
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