Roselita
Roselita is a mineral with formula Ca₂Co(AsO₄)₂·2H₂O, in the Arseniatos group. This specimen comes from Distrito de Bou Azzer, Tazenakht, Ouarzazate, Drâa-Tafilalet, Marruecos and joined the Terrium collection in 2025.
Description
Well-defined crystals on a fracture surface. Very dark fuchsia colour, intense and homogeneous.
About Roselita
Hydrated calcium–cobalt arsenate; cobalt gives the colour. At Bou Azzer it occurs with well-defined crystals, highly saturated colour and associations that have made it a classic reference for the species. It is the cobalt-rich end-member of the roselite (Co)–wendwilsonite (Mg) series; both minerals share a crystal structure, but the dominant cation differs.
About the locality
It is the most important locality in the world for roselite, noted for specimens with well-defined crystals and saturated colour.
Technical data
- Catalogue No.
- 0051
- Composition
- Ca₂Co(AsO₄)₂·2H₂O
- Name
- Roselita
- Group
- Arseniatos
- Category
- Cavella
- Mine
- Distrito de Bou Azzer
- District / Municipality
- Tazenakht
- Province
- Ouarzazate
- Region
- Drâa-Tafilalet
- Country
- Marruecos
- Size (cm)
- 5 x 4 x 3
- Weight
- 38 g
- Acquired
- 2025
- Etymology
- From the surname of the German mineralogist Gustav Rose. The suffix "-ite" is the usual form for minerals. Roselite was first described in 1825.
- Quality
- Muy buena
- Value trend
- Al alza
Related specimens
- Abernathyita — España
- Abernathyita — España
- Abernathyita — España
- Acantita (Paramórfica tras Argentita) — Marruecos
- Adamita — México
- Adamita — México
- Adamita (Cuprífera) — Grecia
- Adamita — México