NATIVE COPPER & UNKNOWN FLUORESCENT

I acquired this slab from an old "rockhound"-type collection; it is largely native copper with a pinkish-tan-colored mineral that fluoresces vividly(short wave UV). Any one know what this mineral might be? I also don't know the locality, but I'm suspicious that it's from either Michigan or Arizona. Size of slab: 8.0 x 4.0 cm.

William C. (CHRIS) van Laer: "I'm using the chicken to measure it..."



Edited 1 time(s). Last edit at 03/20/2012 06:03PM by William C. van Laer.

I once had a similar piece that was alleged by the seller to be from "New Mexico", but I never had any luck pinning it down to a more specific location, so I left it with a club as a give-away specimen for the kids, so unfortunately I don't have it any more for further comparisons, but add NM to your list of possible states.

What color is the flourescence?

Doesn't remind me of any of the Michigan coppers that I have ever seen. I would suspect that it came from one of the southwestern states (Arizona, New Mexico, etc...) if it in fact comes from the US.

I haven't a clue what the fluorescent mineral might be.....

It looks a lot like a fluorescent calcite from the Kelly Mine, Magdalena District, Socorro Co, New Mexico. Copper and cuprite are included in the list of minerals. Just a wild guess! Gary

I once purchased, and eventually traded, a very similar piece. It was labeled Cotopaxi, Colorado. I got it from a rock shop in Canyon City, which was going out of business. I had never even heard of Cotopaxi before and thought the slab was cool. When I could not verify the locality, I traded to a fluorescent collector who didn't care about the local.

I feel like a dufus! Never saw or opened the links to your images. I'd say calcite for the fluorescent mineral.

Steve

Try a drop of hydrochloric acid on the white mineral. If it fisses it is probably calcite.

This looks odd to me. If I look at the white light picture, it looks like a slab of mostly copper. If I look at the UV picture, it looks like the mostly copper stuff (but not all of it, and including some of the other stuff) is fluorescing. That makes no sense!! Copper should not fluoresce... HOWEVER, I know that I may have two relevant pieces. One of them is similar in that it definitely has native copper along with some sort of white mineral. Sadly, I too have no idea where it came from. I only thought native copper appeared in this quantity in Michigan, so I have always considered it as coming from there. Anyway, under SW UV all the white stuff fluoresces red. I am pretty sure it is all calcite. The other piece(s) are pure copper that fluoresce green/yellow. Again, this makes no sense because copper should quench fluorescence. Well, it turns out that *I* am the source of the fluorescence. When I cleaned the copper in sulfamic acid, some new mineral was created and coated some of my specimens, and this new mineral is fluorescent. I am quite sure of this as I let the bucket of acid evaporate and the stuff left over fluoresces exactly the same color.

Sooooo, I am wondering if the fluorescent copper here is really the result of some kind of cleaning byproduct.

Doug