FMF - Friends of Minerals Forum, discussion and message board

[Frank Perry]

I acquired this specimen in the late 1970s and over the years I have lost/forgotten any information on its locality. I vaguely think it's from the Joplin tri-state area (because, hey, its sphalerite!) but that could be totally wrong and misleading. I am fairly certain it's from the USA given the circumstances of acquiring it.

The largest quartz crystal is about 20mm in length. There are other quartz crystals (many doubly terminated) are of half that length to only 2-3 mm that mostly occur in small clusters (not so visible on the photos). The sphalerite crystals are up 7 or 8 mm and are translucent to semi-transparent.

I've looked all over the internet and cannot find anything that looks quite like this specimen. I did come across one example of the doubly terminated quartz from the Empire State Zinc Mine, Balmat, New York (a more recent find?). Those sphalerites seem a lot more gemmy and lighter colored that in the specimen ai have. Doesn't seem like a good match and rings absolutely no bells for me.

Any thoughts on where this might have come from?

[alfredo]

Frank, could that possibly be garnet instead of sphalerite? Check whether it can scratch a glass bottle. (Scratching a bottle will generally make you fewer enemies than scratching a window.)

[Frank Perry]

Alfredo, My first thought was "no way!"

But, it DOES scratch glass and a steel knife point does not scratch the crystal faces, so I guess sphalerite is ruled out.

I did a quick water displacement specific gravity test and got 4.8, so a little greater than garnet? The sample as a whole has a relatively thick matrix and I don't know what all is hidden in the matrix, but it looks to be mostly massive "garnet", so I think 4.8 is probably close to the specific gravity of the crystals. The effect of the small volume of quartz would I think be negligible.

So assuming now that it is garnet (any other possible candidates?) and we have doubly terminated quartz on garnet, anyone have ideas on a locality? Does this open it up to so many possible locales that it would be impossible to pin down?

Thanks Alfredo for getting me off of the wrong track of sphalerite.

[Frank Perry]

p.s., I was so locked into thinking it was sphalerite over the years that it never occurred to me to consider it could be something else.

[alfredo]

Reminds me of this locality, although I suppose there could be many others:
https://www.mindat.org/photo-301639.html

[Jordi Fabre]

As Alfredo well said, it reminds the Vesper Peak Grossulars with Quartz

[Frank Perry]

Looks promising. I found other photos from this locality online and they look similar to my piece, so I think its on right track. I was definitely on the wrong track!

[Michael Shaw]

Species changed to Grossular.