Maybe a hardness tester would help.
I found a piece of metal in the trash 2 weeks ago that I thought was brass, so I threw it in my scrap bin.
It was pretty dirty and I hadn't examined it closely until today. Something wasn't right with the color, so I cleaned it up.
Nope, not brass, 18.2 oz. of silver.
Spot value of scrap silver today made it worth just over $300.00
Not a bad day dumpster diving.