Well, this is a tricky question. While I was searching alone I discovered it may be both, but I am not positively sure. You should be able to find the answer on websites that end with .edu
thanks
Fine grain, rough and soft
fine
small
Pure obsidian actually has a glassy texture (grain), with no discernible crystalline structure.
the same shape as a poo
1.Grain Size 2.Grain Shape 3.Grain Pattern
They just used normal coal.
1.Grain Size 2.Grain Shape 3.Grain Pattern
it can be a square
jagged
Grain shape.
fragments