Re: Unknown metallic rock.
It looks like quartz and mohawkite to me - a rare mixture of algodonite, arsenic-rich copper, and domeykite that's found only in Michigan.
Your specimen looks similar to some mohawkite images online:
Here's the Mindat page for it: http://www.mindat.org/min-2740.html
Hope this helps.
From AJ - March 05, 2012 at 08:15:00