What’s going on with this rock?

[teachbecca]

Found in Ohio,in a field,in N Central area. The black streaks are neat in this rock but I have no idea what they are Some are a flat black color and there are some black shiny crystals too?? What’s this all about? What’s it made of? Thanks for your help!

 

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[fuss]

Could be a hornblende mineral is likely the flat black crystals, shiny black is usually Biotite mica, though I don't see any in the pics. Looks to be a pegmatite rock.

 

[Clay Diggins]

It is a Pegmatite. Not a type of rock but a form of mineralization that creates very large crystals due to slow cooling with high water content.

From the picture the rock itself appears to be composed mostly of Feldspar and Schorl (black Tourmaline).