Althausite , Hematite , Lizardite Locality: Overntjern Quarry, Overntjern, Modum, Buskerud, Norway Dimensions: 8.0 cm x 4.0 cm x 3.0 cm Dark reddish brown, subhedral crystals of althausite to 3cm in a serpentine-talc matrix with dark gray subhedral hematite crystals and aggregates to 2cm. A very good example for the species. Ex. Paulo Matioli collection. Photos by Tom and Melissa Campbell. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Althausite
A very rare magnesium phosphate originally found in magnesite deposits within serpentinite, named for mineralogist Egon Althaus.
Intro adapted from Wikipedia (CC BY-SA).
Althausite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mg₄(PO₄)₂(OH,O)(F, ).
It crystallizes in the orthorhombic crystal system (space group Pnma).
Key properties: Mohs hardness 3.5–4; specific gravity 2.97; Vitreous luster; optically biaxial.
IMA symbol Ahs, IMA status: approved, named in 1974.
Found in serpentine–magnesite deposits (Norway).
It is found associated with Apatite, magnetite, xenotime, holtedahlite, szaibelyite, talc, magnesite (Tingelstadtjern quarry, Norway); apatite, enstatite, talc.
The mineral was named to honor Professor Egon Althaus (1933–), Karlsruhe University, Karlsruhe, Germany.