FMF - Friends of Minerals Forum, discussion and message board

[Juan Roberto Rivera]

Just wanted to confirm that this is an Elmwood piece. It had no provenance card when purchased but it looks like Elmwood to me. Will attach multiple pics. Thank you in advance for your help.

[Juan Roberto Rivera]

more images

[bob kerr]

If the matrix is covered by descloizite - can't tell for sure - then it's a really good bet that this is from Mapimi, Mex.

[Peter Megaw]

There are a lot of possible sources based on the fluorite shape and color...but the matrix looks wrong for Ojuela. I think the red is not a coating but actually makes up the matrix as a layered granular slab...I suspect it is sphalerite...which should fit for Elmwood. The calcite looks wrong for Ojuela too, usually the calcite with Ojuela fluorites is blocky and often included with dak brown gunk.

Check out a few things first...

1. Hit it with LWUV ...many, but not all Ojuela fluorites luminesce a deep red color.

2. Likewise many Ojuela calcites associated with fluorite luminesce orange-red.

3. Scratch an inconspicuous place on the matrix and smell it...if it's sphalerite it will smell sulfrous like rotten eggs.(Sphalerite mnemonic "the streak reeks")

4. If it's sphalerite it may also be luminescent.

Please report back on the results of at least some of these tests

[Jordi Fabre]

Dan Weinrich kindly provides us with this response:

From the pictures, it looks like typical material from the Harris Creek District in Illinois. Probably Denton mine, though could be Annabel Lee.
Not even close to Elmwood though.

[Peter Megaw]

Geographically that is correct...but geologically Illinois is closer to Elmwood (MVT sensu latu) than Mexico (CRD). That red sphalerite is a good sign of MVT

[Herwig]

Since we're in a beginners' section of this Forum, maybe it's a good idea to explain the abbreviations used.

MVT stands for Mississippi Valley Type
More info here: https://en.wikipedia.org/wiki/Carbonate-hosted_lead-zinc_ore_deposits

CRD stands for Carbonate Replacement Deposit
More info here: https://en.wikipedia.org/wiki/Polymetallic_replacement_deposit

HTH
Cheers, Herwig

[Juan Roberto Rivera]

Peter,

I will surely conduct these tests as well for any future specimens that are similar. Thank you for this.

[Juan Roberto Rivera]

Thank you again