Sphelurite of Dachiardite-K from Austa, coll. P. Petrov & Sv. Encheva at the EARTH & MAN NATIONAL MUSEUM, SOFIA, BULGARIA — Photo: Motekov · CC BY 4.0
Dachiardite-K
The potassium member of the dachiardite zeolite series — a rare hydrated potassium aluminosilicate.
Intro adapted from Wikipedia (CC BY-SA).
Dachiardite-K is an IMA-recognized mineral species in the silicate class, with the chemical formula K₄(Si₂₀Al₄)O₄₈·13H₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Dachiardite structural group.
Key properties: Mohs hardness 4; specific gravity 2.18; White streak; Vitreous luster; optically biaxial.
IMA symbol Dac-K, IMA status: approved, named in 2015.
Found in the walls of opal-chalcedony veins cutting hydrothermally-altered volcanic rocks.
It is found associated with Dachiardite-Ca, dachiardite-Na, ferrierite-Mg, ferrierite-K, clinoptilolite-Ca, clinoptilolite-K, mordenite, smectite, celadonite, calcite, barite, chalcedony.
The K-dominant analogue of dachiardite.