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Identity HelpWhat type of iron oxide

6th Dec 2019 00:50 UTCDan Owens

Some quartz from a vein on my place in S.D. with this dark black wall rock with these iron, I assume, spots. What I would like to know are these spots weathered pyrite, or hematite, or garnets that have decomposed? Also what is the black wall rock and the small shiny veins in it. 

6th Dec 2019 00:52 UTCDan Owens

One more pic.

6th Dec 2019 15:50 UTCUwe Kolitsch Manager

You should check both streak colour and hardness.

6th Dec 2019 17:24 UTCDonald B Peck Expert

Agree with Uwe . . . and you might check magnetism also (although I kind of doubt that it is magnetic).

6th Dec 2019 22:47 UTCDan Owens

I checked the streak of the black rock and it was black. Also could scratch with penny. Not magnetic. Could you tell me if it is igneous? It is very fine grained. Put vinegar on small shiny white veins in black rock, but no fizz. The iron must have been in solution when rock cooled to be in spots like that. Whatever it was is now oxidized and lost it's form? Here is a close up.

6th Dec 2019 22:56 UTCKevin Conroy Manager

You may want to contact Tom Loomis.   He's a wealth of knowledge, especially with minerals of South Dakota.   See:  https://www.dakotamatrix.com/home/contact

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