your duty to identify this rock

[huntingforfun12]

I know thats not charcoal!

Charcoal black
Uniform and homogeneous
No big holes or gas bubbles
Top layer charcoally, but lustrous crystal underneath and throughout
Specific gravity 2.9
Found with stones that have pinholes/gas bubbles
Very hard stuff

 

[shaman15771]

Manganese?

 

[huntingforfun12]

Possible! There is evidence of calcite (white) on it
as well making it a little gray on the outside
layer. But, it is pure opaque crystal, maybe of
manganese. Also, when I scratch two crystals
together, the streak is white. Tx for comments.