Arsenolamprite

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Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?



Arsenolamprite
As Orthorhombic

Arsenolamprite is a fairly rare mineral with Mindat showing 18 localities in 2009. Apparently the energy from the Xrays during powder diffraction analysis is enough to cause the mineral to change to Arsenic. Crystals as needles to 8mm and foliated, radial aggregates of plates and massive forms are reported. It is not stated where the 8mm crystals are from or if they were freestanding or not.¹ A mineral similar to Arsenolamprite is Pararsenolamprite. It is stable and maintains its bright lustre, possibly because of its minor Sb content².
1. Handbook of Mineralogy, Anthony, Bideaux, Bladh & Nichols Vol.1 p.26. 2. Alfredo Petrov, email communication 2009.


Arsenolamprite
Chile
Atacama Region, Copiapó Province, Tierra Amarilla, Pampa Larga district, Alacrán, Alacrán Mine
Georg Gebhard brought back a number of specimens with stellate aggregates comprised of individual cleavages well over 1cm long. You can assume I haven't seen the best ones, so there must be larger ones around. These were distributed to species collectors by 2 or 3 dealers, with medium-good specimens costing around $150-$200. Maurizio Dini reports: I visited the mine in February (2009} and it is very hard to get an acceptable specimen. With luck small samples can still be found, but only inside the stopes. 10-15 year ago, there was a great find and crystals up to 2 cm were found (not freestanding). These were the same stellate forms mentioned by Alfredo. They went to the European and American markets. Most of them are intimately asociated (pseudomorphs?) with Native Arsenic. I believe that German xls are more elegant, but Chilean ones are quite competitive too. Alacrán deposit is unique, were other rare minerals may eventually be found.
[Alfredo Petrov 2009]


Arsenolamprite
Czechoslovakia
Krkonoše (Giant Mountains), Černeý Důl.
Arsenolamprite, the supposed dimorph of arsenic, was recently discredited…It is now re-established from a new locality, Černeý Důl, where is occurs as dark gray plates and veinlets in carbonate.”¹
1. American Mineralogist, Vol. 45, 1960 p. 479.


Arsenolamprite
Germany
Hesse, Odenwald, Nieder-Ramstadt, Nieder-Beerbach, Nieder-Beerbach, Glasberg quarry


The specimen pictured above is one of the best found at this locality and exceptional for any locality. The quarry rock ia a gabbro which includes sulphide lenses. Around 1980, a baryte vein with a rich silver mineralization was cut. Collecting is still possible, but many productive zones (in terms of specimens) are collected out. This quarry is also the TL of Fettelite.
[Peter Haas 2009]


Arsenolamprite
Germany
Saxony, Erzgebirge, Marienberg District, Lauta, Vater Abraham Mine ("Shaft 139"; Shaft 152)
The lead picture at the top of this article shows ~2mm crystals of Arsenolamprite associated with quartz crystals. Proustite is also associated on the specimen. Rob Woodside adds: Peter's lovely specimen obviously crystallized as Arsenolamprite, but may now have pseudoed to Arsenic. This instability has led to the discreditation of Arsenolamprite. Frondel who announced things at confrences with no data discredited Arsenolamprite and later reinstated it. Powdering for powder diffraction analysis causes the transformation.


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Rock Currier
Crystals not pistols.



Edited 7 time(s). Last edit at 07/24/2010 08:37AM by Rock Currier.

Peter's lovely specimen obviously crystallized as Arsenolamprite, but may now have pseudoed to Arsenic. This instability has led to the discreditation of Arsenolamprite. Frondel who announced things at confrences with no data discredited Arsenolamprite and later reinstated it. Powdering for powder diffraction analysis causes the transformation.

The 8 mm xls may have been free standing.

There was a rich South American deposit that is still Arsenolamprite, but sadly no xls.

The South America locality that Rob refers to is probably the Alacran mine in Chile, from which Georg Gebhard brought back a number of specimens with stellate aggregates comprised of individual cleavages well over 1cm long. You can assume I haven't seen the best ones, so there must be larger ones around. These were distributed to species collectors by 2 or 3 dealers, with medium-good specimens costing around $150-$200.



Edited 1 time(s). Last edit at 05/26/2009 09:42PM by Alfredo Petrov.

Thanks Alfredo. That's it. The type locality for Alacranite too. I forgot what I paid Rob Lavinsky for my piece which is now in Toronto.

Hello friends:

Alfredo is right about Arsenolamprite from Alacran mine; I have been there last february and it is very hard to get acceptable specimen; with luck only small samples can still be found, but only inside the stopes.

10-15 year ago, there was a one-two time great good find neat and "big" xls, even up to 2 cm, the same stellate aggregates with comprised clivage mentioned by Alfredo, there gone to europe and american market, and most of them are intimately asociated (pseudomorphs?) with Native Arsenic. I believe that German xls are more elegant, but chilean ones are quite competitive too....Anyhow, it is a specimen that in my opinion is not well appreciate by collectors...
Alacran deposit is unique, were rare stuff may be eventuall be found, like those unnamed As:S phases mentioned in the corresponding mindat locality page.

maurizio dini

It might be worth mentioning here that the closely related species Pararsenolamprite is stable and maintains its bright lustre, possibly because of its minor Sb content. Alacran mine has Sb too, so Maurizio, if you find some "arsenolamprite" that stays bright, check whether it might be pararsenolamprite.

This is the best of species. Enjoy !

[www.mindat.org]

Peter,
Thank you for uploading that picture of the Arsenolamprite. I have placed it and the locality in the article. I think you might help educate me as to why the specimen you uploaded is best of species and about Arsenolamprite in general. Tell us something about the locality. A quarry seems to be a strange place to find such a specimen, especially one so rich in Proustite. I would think a silver mine might be a more likely spot. I think a specimen like the one we have at the top of the article might be a more desirable specimen. Are these not freestanding crystals of Arsenolamprite? How many specimens of the species have been found in the Glasberg Quarry? I know I would love to have that good a specimen of the species in my collection.

Rock Currier
Crystals not pistols.

Not particularly this specimen, but the best arsenolamprites, to my knowledge, were found at the Glasberg quarry. This specimen is one of the best that came out. The quarry is rich in silver minerals. It is also the TL of fettelite.

Peter,
What kind of quarry is it? Is it still operational? Do collectors get in to collect from time to time? What do you think of the specimen at the top with the free standing crystals?

Rock Currier
Crystals not pistols.

The quarry is in a gabbro which includes sulphide lenses. Around 1980, a baryte vein with a rich silver mineralization was cut. Collecting is still possible, but many productive zones (in terms of specimens) are collected out.

Thanks all. I have incorporated your wisdom and much of what you relate above in your posts has been translated into the article on Arsenolamprite.

Rock Currier
Crystals not pistols.

Hello,

Then there has been discovered one specimen from Sophia Mine, Wittichen, Black Forest, Germany from an old collection. I will look up the a rticle (it was Lapis, if I'm right). Arsenolamprite occurs together with dendritic aggregates of native silver there. It's a very rare finding, so far as I know this piece is the only one known from there.

Regards,
Sebastian Möller