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Improving Mindat.orgBenleonardite, cervelleite, stutzite from Moctezuma

16th Jun 2017 21:22 UTCJeff Weissman Expert

Stanley, Criddle and Chisholm describe benleonardite (Min. Mag. v50, 681, 1986) and cervelleite (Eu. J. Min. v1, 371, 1989) as both occurring as sub-millimeter to micron-sized intermixtures with native silver, acanthite, hessite, pyrite and sphalerite, with dolomite and quartz as thin (1-2 mm) black and crumbly fracture fillings in an highly altered silicified 'rhyolite vitrophyre'. They do not describe any other minerals containing Ag-Te (i.e. stutzite), although other Ag-Te minerals can be present in others specimens not studied by these authors.

I can find no references to or reports of an analysis of stutzite from Moctezuma or any of its mines. Having this information would be greatly appreciated and will help to clarify or correct my comments, below.

This one is, of course, correct for cervelleite, hessite, and acanthite - https://www.mindat.org/photo-649603.html

I suggest that the following images be examined and corrected as necessary:

https://www.mindat.org/photo-26572.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than cervelleite

https://www.mindat.org/photo-727068.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than cervelleite

https://www.mindat.org/photo-326248.html - how was this identified to be benleonardite? other Ag-Te-S minerals present?

https://www.mindat.org/photo-597188.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than benleonardite

https://www.mindat.org/photo-701628.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than benleonardite

https://www.mindat.org/photo-169921.html - this looks like native tellurium only

https://www.mindat.org/photo-213729.html - most likely this is hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, hard to tell due to image quality

https://www.mindat.org/photo-380973.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than stutzite

https://www.mindat.org/photo-677994.html - hessite with possible inclusions of cervelleite and/or benleonardite, and acanthite, rather than stutzite

for the two hessite specimens, images https://www.mindat.org/photo-785099.html and https://www.mindat.org/photo-785107.html (are these the same specimen?), a report on the analysis would be appreciated, note that the physical appearance does not fit the description in the above referenced papers.

specimen https://www.mindat.org/photo-311789.html was found to be hessite, although it was originally labeled as 'aktashite' (Cu6Hg3As4S12), which underscores the difficulty in identifying these black blebs from Moctezuma

16th Jun 2017 22:43 UTCFrank Keutsch Expert

Thanks Jeff, I agree. Without polished mount and detailed analysis the assumption should be that the phases are common. I have analyzed numerous aktashites, stutzites, cervelleites, and benleonardites and have not been able to find these phases even once. However, this does not meant that the specimens in question are wrong at all, but without analytical results one should assume that they are hessite, tellurium etc. and if the rare phases occur, probably as inclusions.

Frank

16th Jun 2017 23:03 UTCBrent Thorne Expert

Specimen #213729 was purchased form Dakota Matrix Minerals with a previous label from Cureton Minerals. I do not have any analytical data on the specimen so I have removed it from the public galleries.

Specimen #326248 labeled as benleonardite was acquired from Dr. Wilke in Germany who got the specimen from Sid Williams. There is a note with the specimen that it was microprobe analyzed by Sid. The label mentioned hessite occuring with the benleonardite. Because of Sid Williams reputation for theoretical minerals on a specimen, I will also remove this photo from the public galleries.

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