I was hiking in the backcountry in Crested Butte, CO and came across an old mine and started looking around for something. Here are some of the rocks I came back with. Is it silver? I haven't done any tests.
Ok, a method you may or may not have the materials to do: Pulverize a small sample. Boil for a couple minutes in dilute nitric acid. When solution is cold, decant off and add a pinch of common table salt and stir. If the solution turns milky white and settles to the bottom, drain acid and wash with distilled water. Boil for a couple minutes in distilled water. Anything remaining is PROBABLY silver.
It was those lined striations on the facets of the cubes that's the clue to my assessment as what it might be. It does look a little grey though. Plus maybe some patina being exposure to the air I'm thinking. Years back I sorted thru the mine dumps in Leadville Colorado. I took samples to an assay office in Alma Colo. that was open back then. The guy gave me tips on what to keep an eye out for. Rich ore samples would be lost off the ore cars or put aside from the mine tailings dump for some reason or other? I think also some new hire muckman would get confused over what was good stuff over waist, thinking he'd get allot more hell if he diluted the mill with waist, so to be on the safe side, he'd just dumped the whole car in the tailings. Who's going to know? and for $2.50 a day it wasn't worth getting canned.