what are these black veins in these rocks ?

[matthew textor]

hi everyone this is matt again

does anyone know what these veins in this rock are 

they are brown and shiny and they are all over the rock 

there are 4 peaces from the rock and here are photos of them 

 

 

 

 

[Brett Breakin' Rocks]

1 hour ago, matthew textor said:

hi everyone this is matt again

Hi Matt, I'm not as familiar with hardness tests but does it look like there is some quartz in there ? The photos aren't crisp online (or I need glasses) so I can't tell. Is it really brown ? .. they look dark grey in the photos. Galena and Pyrite can be associated with quartz and both can have a metallic 'sheen' .. and Pyrite often changes color when exposed to the air for long periods of time.

 

Are the shiny bits flaky (like mica)  ? .. or rather hard

 

Do we have a location ?

 

Edit: the photos are not the best but @ynot is a rock guy too.

 

Thanks,

Brett

[Misha]

Maybe biotite?

[FranzBernhard]

Tough question!

The rock looks like a coarse grained granitoid or pegmatoid rock.

In the first pics, some spots look like a somewhat tarnished sulfide. Pyrrhotite or chalcopyrite come to my mind.

In the last pic, the areas in question look like biotite, which is also my preferred interpretation.

So please try some simple tests:
- Is the mineral platy, sheet-like, can the sheets be bend without breaking?

- What does the powder of the mineral in question look like?
Franz Bernhard

[matthew textor]

I now know what this rock is it is called mica