FMF - Friends of Minerals Forum, discussion and message board

[Pete Richards]

You're right, Peter - pyrrhotite is found replaced by either pyrite or marcasite at Mont Saint-Hilaire - I have found both on the same specimen. Both are commonly oriented replacements (topotaxy), which adds to the interest and the esthetics of the samples. The one drawback is that they're almost always micros. I don't seem to have any photos of the pyrite after pyrrhotite, but I think you'll like this one of marcasite after pyrrhotite.

[Jordi Fabre]

More Spanish localities: Brunita Quarry and Los Blancos Quarry both in the Cartagena-La Unión mining district as well as the Lomo de Bas tunnel in the works of the highway between Cartagena-Vera, Murcia, Spain.

As Peter can read Spanish language, for the details please visit this post: https://www.foro-minerales.com/forum/viewtopic.php?p=18852#18852

Jordi

[mmauthner]

Peter,
The question is not so much about Keno Hill (Galena Hill, actually, in this case) as it is about this one specimen. I have never seen others, nor read about the occurrence of pseudomorphs in these mines. To my knowledge...there is just so little literature on what has to have been one of the 20th century's major silver camps...no one has written about it (pseudomorphism/replacement) or maybe even taken note of these features.
I'll get a picture up as soon as I get my new iMac back from the shop (the irony is disgusting).

I shall also have to get an image scanned of one of the Nanisivik specimens. There is no possible confusion that this is a pyrite (or marcasite) pseudomorph after pyrrhotite. There are Py ps after cyclically twinned marcasite, but these are quite distinctive and the angles are all wrong to be after pyrrhotite.

Cheers,
Mark

[Jesse Fisher]

Hello Peter,
The Cambokeels Mine in Weardale was famous during the 1980s for producing some of the best pyrrhotites found in Britain. While I don't have a "killer," I do have several small specimens of what morphologically appears to be pyrrhotite rather than pyrite. None show the slightest magnetism so I am assuming that they are now pyrite pseudomorphs. While a typical MVT-type deposit like others in the region, the Cambokeels Mine was the only one I am familiar with that produced pyrrhotite in the orefield. It was also one of the deepest mines in the region and closed when the lowest levels were literally meters from penetrating the underlying granite.

Cheers,
Jesse

[Peter Megaw]

Jesse...would like to see it next time I'm out there,...or a picture sooner. Would note that there are non-magnetic polymorphs of pyrrhotite, so magnetism alone is not definitive...

[Jordi Fabre]

Peter,

Please add to the list the locality of El Hamman, Meknes, Morocco. As soon as I can I will publish a photo of a very nice example from there.

Jordi

[Jesse Fisher]

Peter,
Here is a photo of pyrrhotite from the Cambokeels Mine in Weardale. The field of view is about 2.5 cm across. I'm pretty sure it at least pyrrhotite to begin with as a number of sections on the surface appear to be "tiled" with small hexagonal plates. As mentioned, no hint of magnetism.

Jesse

[alfredo]

You're probably right about the pyrrhotite, Jesse, but just in case, check the streak. There are some weird metallic-tarnished wurtzites in Bolivia that have that same stacked-hexagonal-tiles appearance, and a nice black streak would ensure that that tiny bit of doubt could be eliminated.

[Jesse Fisher]

Dark gray/black it is.

[Jordi Fabre]

Here you have the promised image of a Pyrite after Pyrrhotite (and Pyrite coating) from the Fluorite mine of El Hamman, Meknes, Morocco.

Jordi

[Peter Megaw]

Cool pictures guys, great discussion...keep it up PLEASE

[alfredo]

Peter, If you were a subscriber to Rocks & Minerals back in 1998, there was an article on a variety of pseudomorphs from Bolivia in vol. 73, # 6, pp 410-414.

[alfredo]

Am currently enjoying the Rochester Symposium in western New York state. A few other FMF friends are here, including John White, and Gail. In the display cases there are a number of fine pseudomorph specimens that might be relevant to Pete's study:

Siderite @ pyrrhotite - Turt, Rumania
Siderite @ calcite - Turt, Rumania
Galena @ pyrrhotite - Herja, Rumania
Siderite @ calcite - Gheturi mine, Rumania (Not in Mindat; do you know it, Jordi?)
Siderite @ calcite - Boldut, Rumania
Siderite @ calcite - Broken Hill mine, Aggeneys, South Africa
Tennantite @ chalcocite - Tsumeb
Tennantite @ enargite - Anselmo mine, Butte
Stolzite @ scheelite - Thompson mine, Darwin, CA

[Jordi Fabre]

Another image of a Pyrite after Pyrrhotite from Sultana Quarry, Cartagena, Murcia, Spain. On this case covered by Sphalerite.

[Azogue]

I am rather late to enter the discussion!

Anyway, I just fell on your question: "does anyone know of a Sn component in (a few world ore deposits) and Trepca.

The answer for Trepca is YES. Stannite (but just a little!). The run of mine ore contains around 36 ppm Sn.