Oddly colored previously assumed pyrite nugget very soft, holding under 14, 18, 22k and platinum acid? What could it be? Platinum and copper?
Hello,
I found what I thought was a piece of Chalcopyrite in a box of old core samples and other stuff that I got from an antique store on the west coast a few years back.
I was holding it recently and realized that it was dented by my fingernail so I decided to give it a streak test. To my surprise, I found it to be extremely soft. It holds under every acid that I have, even 22k and platinum to the point where nothing will get it off of my scratch plate now. The outside looks very much like pyrite/chalcopyrite but the inside does look more gold colored. It also has some whitish silver streaks throughout that are also soft and leave a metallic silvery white streak that also holds under every acid that I have.
In terms of the reactions to the acid, lt has very minor smoking under 14k acid, it starts to lift a bit under 22k and also gets some whitish streaks under the 18 and platinum acids. It was a solid nugget before I tested and when I hit it with a hammer, it broke in half revealing the brighter gold interior. Also, I gave it a polish and it polished like gold, very easy to put a mirror finish on it.
Last photo is streak color of the silver parts. Streak plate is all the acids as indicated by the number of the streak-