Fizélyite - Herja Mine, Chiuzbaia, Baia Mare, Maramureș Co., Romania

This unfortunate photo has two complaints. One by Peter Haas in 2005 and one by me in 2010. Peter complained about the original description and unaware of Peter's complaint or the original description, I chimed in. In Peter's complaint he says the fuzzy grey has been well analysed as Jamesonite. I first saw this material on Ross Lillie's website. I contacted him and he was heart broken that these were not Fizelyite, but an analysed boulangerite pseudo after fizelyite. They would have been Killer Fizelyites. So what is with this material? Some of it seems to be analysed as Boulangerite and some as Jamesonite. How about the Jamesonite included Calcites from Herja? An EDS will sort the two by the tiny but above background Fe peak in Jamesonite.

Hello Rob,

Are all of these fuzzy Fizelyites pseudos? I've seen some for sale which claim they are jamesonite/boulangerite on Fizelyite.

Hi

I have a specimen which does much resemble that of Peter Haas (http://www.mindat.org/photo-31746.html)
In my case, some of the prismatic crystals in the radial fans (to 15 mm) of "Fizelyite" were indeed Fizleyite fully coated by felted powdery Boulangerite / Plumosite (no Jamesonite) and Semseyite (both species confirmed by SEM-EDX). In other crystals of the fans, it looked that the pseudomorphosis (?) to Boulangerite/Semseyite was complete, as no more Fizleyite was detected. There was additional small Freibergite crystals on Sphalerite ore.

jf

Hi Reiner and JF

Apparently this material was the last gasp of Herja and came out just before it closed. The fuzzyness is a sure sign of pseudomorphosis and JF's report is the first I've heard of a partial pseudo. Looking at Peter's photo:

Fizelyite pseudo	© Peter Haas

There's a broken xl on the lower right in the fan that looks like the partial pseudo that JF describes. Historically (Dana 7) the fizelyite from Herja were unterminated lathes. Semseyite which always? was associated was more tabular with equant arrow like terminations or cockscomb growths. Historic specimens had no fuzz and the fizelyite was greyer than the black semseyite. The fan in Peter's photo is reminiscent of a semseyite cockscomb but the xls are longer like fizelyite. The Van Silver terminated Fizelyites are not so equant with one of the terminal faces much larger. So possibly Fizelyite and Semseyite came in at a low temperature and a higher temperature later event brought in the tetrahedrite and caused the pseudomorphosis to Plumosite and? Semseyite. JF, was there semseyite in the fuzz on Fizelyite. I'm asking if the semseyite was an original mineral or part of the pseudomorph? Plumosite is a well chosen name as some of it was Boulangerite and some Jamesonite and that seems the case here.

Freibergite has had a sad history of being an Argentian Tetrahedrite (Dana 7) to a full species status today. Most older labelled Friebergites are tetrahedrites with a bit of Ag. Over 20 years ago when I was looking at this I remember the figure of merit being 28% by weight Ag. (The Van Silver Tetrahedrites came in at 26% and have red internal lights like Binnite). Since then there has been an almost pure Ag tetrahedrite from Russia. There are a couple of metal sites in the Tetrahedrite structure, but I think they have been lumped to define the current Tetrahedrite nomenclature. What is the wt % of Ag needed these days for real Freibergite?

Hi,

Thanks Rob for this warning. Sure, the problem can not be generalized. It might say that these partial / total pseudomorphosis depend on the density of mineralization solutions, temperature etc. Also that individual crystals do not seem ''prone'' to these transformations. On the other hand, the Fizelyite radial aggregates seem to be affected. Specimen ID 427298, 427296 (n. 493 ), self collected and analized much later show no sign of change, aggregates are strongly deformed, poorly coverage, association with small Baryte and Calcite as well. Certainly, another occurrence. About the specimen discussed, that's strange the thiny external cortex Boulangerite between radial Fizelyite.
About ''Jamesonite included calcites from Herja''-certainly the Herja black calcites appearance, with their slightly curved shapes, as a consequence of jamesonite rich solution formation. Many specimens were identified and confirmed as Virgil Ghiurcă (2005) studies.

Regards,