Unknow from Tsumeb

Platy, pale brownish, <0,1 mm crystals in a vug into the Germanite. A Söhngeite? Other ideas?


Simone Citon

Hi Simone,

I think it could be tsumgallite, I have a similar one from Tsumeb. My sample seems a mica-like mineral under the scope, probably like yours.

David Hospital

Hey Simone!

Great find! I agree with David - TSUMGALLITE! I had material that looked exactly like this that we had analyzed and confirmed. That is a fantasic find indeed! Nice work! Certainly worth an analysis!

Just out of curiousity, is this the only area on the specimen that hosts this material? Are there any other species present?

Hello Simone,

The tsumgallite that I have is intimately associated with sohngeite, siderite, quartz, galena, tennantite, germanite, and renierite. The crystals are tan platy crystals with a pearly lustre. The crystals, that are shown in the photo, seem to be more clear than tan opaque. I would suggest a simple SEM EDS analysis to see if there is gallium in the structure.

Brent

Hi and thanks to all! Another pic of this Tsumgallite (?), hard to say if the edges of the flattened crystals are more rounded or squared: it seems both...


Yes, dear Jasun, there is a lot of minerals in this specimen. I see white, partially translucent material, I don't know is can be just Cerussite...


And an interesting near to black, but with deep red points in the fracture, mineral. Sometime I see triangular crystal section, as in the pic, I don't know if can be just a Cuprite...


Simone Citon



Edited 1 time(s). Last edit at 03/11/2013 07:19PM by Simone Citon.

Two side of another crystal like the last, partially well formed, seems cubic, just under the mm in size:




Simone Citon

The metallic mineral with deep red internal reflections could well be Tennantite - this is not an uncommon feature of low-Sb and -Fe Tennantite (such as some samples from mixed Ge-rich Cu ore from Tsumeb). This also explains the rough triangular outline; it's probably a tetrahedral face. I don't think it can be Cuprite in this paragenesis.

The pale tan platy mineral in the second photo ("tsum.jpg") appears to be different from the first scaly one, identified as Tsumgallite. Tsumgallite xls show a strong pearly luster and consists of very thin, wispy flaky xls - different from the ones in the second photo. It could be a plain carbonate (in very flattened "disc-shaped" rhombs) or something completely different, of course.

I have no idea about the transparent granular mineral, but the direct association with reddish-grey metallic Germanite looks promising.

Lefteris.