FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Hi,
What are the rarest mineral collections?
I propose today buttgenbachite, already known for a long time (1925).
Its rarity derives from the fact that it is soluble in water. This copper chloronitrate has been found in Panda mine, Likasi (DR Congo), enclosed in masses of crystalline cuprite.
Roger.

[Jordi Fabre]

Great topic Roger (and lovely specimen!)

I would like to add something which could appear not so rare because it is a Borate, but according the Mineralienverzeichnis it has three stars rarity so even rarer than the Buttgenbachite (two stars ;-)

[Pete Modreski]

Yes, and that's a very pretty photo of it! Not a mineral I was familiar with; thanks for sharing the photo.

[Gail]

We love it. Jordi was kind enough to post, thanks my friend!

[prcantos]

The mineral 'phosphoellenbergerite' is a rare phospate described the first time at Dora Maira Massif ultra-high pressure metamorphic coesite-bearing pyrope quartzites.

[Roger Warin]

Thanks,
This buttgenbachite specimen was exhibited to the 45th Intermineral Liège Show, on the occasion of the International Year of Crystallography. It is a piece that Buttgenbach had in his museum of the University of Liège.
Roger.

[Tobi]

Actually I thought I was a mineral expert ... but hearing about things like buttgenbachite, phosphoellenbergerite and strontioginorite makes me doubt this ;-) And as a collector of aesthetic classics I can't contribute to this thread. I guess the "rarest" thing in my collection, compared to all the fluorites and galenas and quartzes, are the small bertrandite crystals I have on a smoky quartz from Kara Oba ;-)

Roger, though I never heard of buttgenbachite before, I really love your first photo, would you provide it in higher resolution for use as desktop wallpaper?!

Tobi

[Roger Warin]

Tobi,

Thank you for your kind words. Obviously I share your opinion.
I want this photo (higher resolution) is not vulgarized. I give it personally. I took this picture there are more than twelve years and I still have not found the original file.
Give me your email address.
Roger.

[Roger Warin]

Thoreaulite

This mineral was determined by Buttgenbach in 1933.
This specimen is perhaps the best known for this exotic species.
It is related to coltan, except that (Fe, Mn) are substituted with Sn2 + to give
Sn 2+ (Ta, Nb) 2O6.
Tantalum and niobium are associated with tin, it is not usual.
Crystal obviously very rare.
Roger.