Holmquistite

Holmquistite is a lithium magnesium aluminium inosilicate mineral with chemical formula Li₂(Mg,Fe²⁺)₃Al₂Si₈O₂₂(OH)₂. It crystallizes in the orthorhombic crystal system as prismatic crystals up to 10 cm (3.9 in) or as massive aggregates. It has a Mohs hardness of 5–6 and a specific gravity of 2.95 to 3.13.

Holmquistite
Holmquistite from the Foote Mineral Co., Kings Mountain, North Carolina
General
Category	Inosilicate
Formula	(Li2)(Mg3Al2)(Si8O22)(OH)2
IMA symbol	Hlm[1]
Strunz classification	9.DD.05
Dana classification	66.1.2.9
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M Symbol: (2/m 2/m 2/m)
Space group	Pnma

Color could vary from black, dark violet to light sky blue.

It occurs as metasomatic replacements on the margins of lithium rich pegmatites.

It was first described in 1913 from an occurrence in Utö, near Stockholm, Sweden. It was named for the Swedish petrologist Per Johan Holmquist (1866–1946).^[2][3]