Can someone ID this please- Thanks :)

Question

Answer 1

Obsidian maybe, where did you find it. Like Reno, Nevada in a dry riverbed.

Answer 2

To me, the fractures do not look like obsidian. Is it magnetic?

Answer 3

This specimen has crystal faces therefore it cannot be obsidian, which is amorphous. The luster, form, and cleavage from the photo indicate a mica, most likely in the biotite family. Can you peel off layers or put a knife blade inside it?

Answer 4

Looks like some sort of Biotite Mica.  Either way it’s a nice find :))