Black streaks in rock

[Bmerck]

At one time it was one big piece i broke it with a hammer to see what the inside looked like saddly i have no picture of it besides the ones showing after broken just wanted to see what it could be. Any thoughts?apart

 

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[Steve1236]

Hard to tell from a picture but it looks like it could be galena in quartz, scratch the dark metallic mineral against unglazed porcelain, back of the toilet lid will work and see what color the streak is, that will help with identification.

 

[Buckshotnc]

Top middle picture looks like the dark material could possibly be manganese like we have in Western North Carolina.