Armenite Locality: Isenwegg, Wasen Alp, Ganter valley, Simplon pass area, Brig , Wallis (Valais) , Switzerland ( Locality at mindat.org ) Size: 3.2 x 2.2 x 1.5 cm. Armenite is exceptionally uncommon, especially in large euhedral crystals. This piece has glassy, lustrous, white crystals of armenite to 1.3 cm on matrix of smaller crystals. This is a rare hydrated, barium, calcium, aluminum silicate from the famous Simplon Pass, in Switzerland. This fine specimen was found in a freak and lucky find of the early 1990s. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Armenite
Armenite is an IMA-recognized mineral species in the silicate class, with the chemical formula BaCa₂(Al₆Si₉)O₃₀·2H₂O.
It crystallizes in the orthorhombic crystal system (space group Pnna). It is a member of the Milarite structural group.
Key properties: Mohs hardness 7–8; specific gravity 2.74–2.76; Vitreous luster; optically biaxial.
IMA symbol Amn, grandfathered status — known before the IMA’s founding, named in 1939.
Found in calcite veins (Kongsberg, Norway); in manganese-metasomatized diorite included in later granodiorite (R¶emigny, Canada).
It is found associated with Axinite, pyrrhotite, quartz (Kongsberg, Norway); albite, manganiferous zoisite, piemontite, prehnite, epidote, muscovite (R¶emigny, Canada); celsian.
The name refers to the Armen mine, Kongsberg, Norway.