FMF - Friends of Minerals Forum, discussion and message board

[lidaasteria]

Hello all.....

We've been finding quite a mix of specimens that come out of the Walker Vein (Boyle County, KY..Caldwell quarry)

We can identify Baryte, calcite, sphalerite...but having trouble determining if the yellow minerals are pyrite, or something else?

There might be more going on with these rocks than we realize, and hope somebody here has a good eye.

Some of the sphalerite glows a reddish-orange under short-medwave UV. Is it possibly coated with calcite?

Thanks for your help:)

Robert

[Pete Richards]

I don't see anything that looks like pyrite. The only yellow mineral I see appears to be sphalerite - the stuff that is fluorescing the most brightly. Incidentally, it appears to me that the last two images are of the specimen, but one is upside down relative to the other. Is that correct?

[lidaasteria]

Yes, I took the three pictures separately, and they're probably not oriented the same.

When I photographed it under UV, I noticed that the red coloration is coming from the black sphalerite. But its only coming from certain areas. Some of the black fluoresces, some doesn't.

When we first started finding these, they came from an area where a lot of pyrite is present. The yellow/gold coloration had us confused.

So, this specimen is made up of limestone, black/yellow sphalerite, calcite and Baryte...interesting:)

Thanks for your help

[lidaasteria]

The following two pictures are oriented correctly...

[Mark Ost]

It certainly fluoresces like sphalerite. See if it sparks when you rub a paper clip across it, demonstrating triboluminescence.

[lidaasteria]

I've heard of that...will have to try:)

[stef4412]

Hi lidaasteria
sphalerite often contain rare metals included, such as cadmium, germanium, iron, gallium, ... eg cadmium is often in the form of inclusions greenockite.
Certainly, these luminescent areas must be caused by abnormal localized concentrations of these metals.
In any case, no pyrite on your photos