Holmquistite is a lithium aluminium with chemical formula Li 2(Mg,Fe2+ ) 3Al 2Si 8O 22(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 2.95 to 3.13.
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. It was named for the Swedish Per Johan Holmquist