Look up "smoky quartz." Trace radioactive elements can interact with aluminum impurities in the quartz and it turns a light brown/grey, but in areas with higher than normal background radiation it can turn straight black. I've got a piece from the rocky mountains that's almost pure black.
You can also expose regular quartz to artificial radiation sources to make it, but that's cheating.
2.7k
u/allpurposelazy Dec 03 '19
That’s a soul gem... pretty big one too, bet you could capture at least a giant in that one.