Can Someone Tell Me What Kind Of Rock This Is?

[Madi9141971]

I found this rock outside of a friends house, it’s very shimmery and the tiny grains are like thin rectangular shards. My best guess is amphibolite but that just doesn’t seem to be quite right.

thanks!

[Madi9141971]

All of the white specs are light reflecting off of the stone, it is completely black other than the layers in between

[jasong]

Looks like biotite schist. More biotite = blacker rock. 

Here's a normal mica schist, now darken it by adding more biotite and that's what your rock appears to be. 

You were on the right track with amphibolite, as it's a metamorphic rock. 

[Madi9141971]

Yes! That’s exactly what it looks like! Thank you! @jasong