9.0 x 5.5 x 5.0 cm. A very good specimen exhibiting white botryoidal kaatialaite, a hydrous iron arsenite, in vugs within a gray-black mass of skutterudite. From the silver-rich, uranium-bearing polymetallic vein deposits of the historic Erzgebirge (Ore Mountains) of the Czech Republic. From the Josef Vajdak collection; he assembled a notable collection of Jachymov minerals. From: Svornost Mine, Jáchymov, Jáchymov District, Krušné Hory Mts, Karlovy Vary Region, Bohemia, Czech Republic — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Kaatialaite
A ferric hydrogen arsenate hydrate found in Finland.
Intro adapted from Wikipedia (CC BY-SA).
Kaatialaite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Fe³⁺[AsO₂(OH)₂]₃·5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: specific gravity 2.64; Earthy luster; optically biaxial.
IMA symbol Kaa, IMA status: approved, named in 1982.
Found as a secondary mineral in a granite pegmatite (Kaatiala pegmatite, Finland); in an oxidized Ag–As vein in gabbro (Niederbeerbach, Germany).
It is found associated with Arsenolite, löllingite, calcite, gypsum (Kaatiala pegmatite, Finland).
The name refers to the Kaatiala pegmatite, Finland, in which it was first found.