FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Another very rare mineral, even emblematic, the buttgenbachite from Katanga.
It appears on cuprite, and is sometimes accompanied by silver.
Roger.

[gemlover]

so fantastic, beautiful specimen. thanks for sharing

john

[John Medici]

Roger, great contrasting group of Cu minerals!

[Peter]

Wonderful beauty and rarity captured!

[Roger Warin]

Many thanks, Peter.

[Pierre Joubert]

That, Roger, is a STUNNER!!!

[valere]

Buttgenbachite is the holy grail for the Congolese mineral collectors
The only specimen I have is the one used and illustrated in the RRUFF database (RRUFF ID: R090013)

https://rruff.info/

That website is a real mine of data, and its buttgenbachite link gives access to the full text of several publications by simple clicks!
Examples with nice needles big enough to be seen with naked eyes are currently out of reach for young collectors, the quest of new samples of new specimens of Buttgenbackite (and related spieces) will be the ultimate goal of my coming Congolese trips! My hopes are intact!

All the best

Val

[domenico]

WAW Roger nice photo and sample !!

[Mark Ost]

So delicate. Thanks for sharing.

[Roger Warin]

Hello,
About buttgenbachite…
All nitrates are soluble in water. This is because of their extreme rarity. However buttgenbachite exists. It can be found only in extreme drought.
Located on the plateau of Haut-Katanga, Likasi (formerly Jadotville) has a mild tropical climate.
In Likasi (DRC), buttgenbachite is found breaking blocks of massive cuprite.
Its origin may lie in aqueous salt solutions of copper. It will crystallize because many hydroxyl anions are introduced into the crystal. Nitrates groups are structurally almost identical to the carbonate anions. Water molecules of crystallization are introduced into the crystal lattice during the growth. But I never try washing this mineral with water...
Buttgenbachite formula is Cu19Cl4 (NO3)2 (OH)32 • 2 (H2O).
The specimen in my photo is exceptional because the needles form a nice spray. Most of the time, it was tangled packets of needles.
Sometimes, silver is found as paragenesis.
Association: Cuprite, likasite, gerhardtite, malachite, brochantite, silver.
Honors Professor Francois Jean Henri Buttgenbach (1874-1964), Belgian mineralogist, University of Li ege, Belgium, who long studied Congo minerals.
Roger.