Torbernita
Torbernita is a mineral with formula Cu(UO₂)₂(PO₄)₂·12H₂O, in the Fosfatos group. This specimen comes from Musonoi, Kolwezi, Lualaba, Alto Katanga, República Democrática del Congo (ex-Zaire) and joined the Terrium collection in 1989.
Description
Good colour, transparency and crystal quality, but irregular composition and a visually unbalanced appearance. Some groups occupy a shallow central cavity. The piece is compact and heavy.
History of this specimen
The base of the box retains an original label with fields in English and French ("pays", "divers", "name"), which suggests a francophone origin—probably an old Belgian collection—consistent with the usual provenance of Musonoi torbernites distributed in Europe in the late 20th century. And by the way, when I received it, I was surprised by the quality of the crystals: large, very green, transparent and with vitreous lustre. But I was a bit disappointed too, because in hand the piece does not have a balanced composition nor that architecture which gives presence to other torbernites lining an earthy matrix. It is also true that the crystals of those torbernites are usually small and fairly crowded, so a few days later, looking at the market, I realised how good this crystallisation is and how little I had paid for it.
About Torbernita
Copper uranyl phosphate; a secondary mineral from the oxidised zones of uranium-bearing veins. Torbernite is distinguished by its intense green colour, vitreous lustre and square tabular habit.
About the locality
Classic locality from which, between 1970–1990, some of the best torbernites known were produced, with intense, bright green, well-formed crystals on brown to dark matrices. Musonoi produced enormous quantities of secondary uranium minerals—torbernite, metatorbernite and uranophane—and for decades fed the European collectors' market, to the point of setting the visual standard for many uranium phosphates now considered "normal". Since the 1990s, with closures and instability in Katanga, little new material has emerged; what circulates today comes from old stocks and from private European collections, above all French, Belgian and Swiss. Like this one.
Technical data
- Catalogue No.
- 0219
- Composition
- Cu(UO₂)₂(PO₄)₂·12H₂O
- Name
- Torbernita
- Group
- Fosfatos
- Category
- Núcleus Ardens
- Matrix
- Matriz dolomítica
- Mine
- Musonoi
- District / Municipality
- Kolwezi
- Province
- Lualaba
- Region
- Alto Katanga
- Country
- República Democrática del Congo (ex-Zaire)
- Size (cm)
- 6 x 3.5 x 3.5
- Acquired
- 1989
- Ex-collection
- Marzio Mamberti
- Etymology
- Named in honour of the Swedish chemist Torbern Olof Bergman (1735–1784).
- Quality
- Muy buena
- Value trend
- Al alza