im gonna go with goldstone too
although i have never seen it in black
ive had lots of orange/brown,some green,red,purple
but never seen it in black before
it works pretty well for knapping,ask Eddie i gave him i nice knife in the x-mas trade that the blade was goldsone
its tougher than obsidion
likes a proper platform or it will crush
you may find spots that seem tougher than the rest
ive found where ever there is even slight color change in the goldstone it changes the flaking characteristics of it a little bit and makes it either tougher or easier
in that area to flake
abraid it and nock out a point or two and lets see 'em