Gmelinite-K from the famous Lovozero region in Russia. — Photo: David Hospital · CC BY-SA 4.0
Gmelinite-K
The potassium member of the gmelinite zeolite series — a rare framework silicate closely related to chabazite.
Intro adapted from Wikipedia (CC BY-SA).
Gmelinite-K is an IMA-recognized mineral species in the silicate class, with the chemical formula K₄(Si₈Al₄)O₂₄·11H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Gmelinite structural group.
Key properties: Mohs hardness 4; specific gravity 2; White streak; Vitreous luster; optically uniaxial.
IMA symbol Gme-K, IMA status: approved, named in 1999.
Occurs as drusy aggregates in cavities within brecciated pegmatite.
It is found associated with K-feldspar, nepheline, sodalite, cancrinite, amphibole, pyroxene.
The name refers to Christian Gottlob Gmelin (1792-1860), mineralogist and chemist of Tübingen, Germany. The suffix indicates the predominance of K as the extra-framework cation.