Mineralpedia Details for Holmquistite

Named for Per Johan Holmquist, a Swedish petrologist. Holmquistite is a rare mineral that occurs as a metasomatic replacement near that outside of lithium-rich pegmatites. Localities fo Holmquistite are found in Sweden, Austria, the United States includeing here in the Black Hills of South Dakota in the Keystone area, Canada, Zimbabwe, South Africa, and Australia, among only a couple others. Minerals assocaited with Holmquistite include quartz, clinoholmquistite, tourmaline, spodumene, plagioclase, biotite, clinozoisite, and tourmaline.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/holmquistite.pdf

Formula

[ ]Li₂(Mg₃Al₂)Si₈O₂₂(OH)₂ 

Crystal System

Orthorhombic 

Crystal Habit

Prismatic 

Cleavage

Perfect, None, None 

Luster

Vitreous (Glassy) 

Color

blue, violet, light blue, dark violet, black 

Streak

bluish white 

Class

Orthorhombic - Dipyramidal 

Hardness

5.5 

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Bluish grey compact, acicular crystals of this rare lithim member of the amphibole group.

Bluish black radiating groups of Holmquistite crystals to over 2cm long. Holmquistite is a lithium amphibole sometimes found in schist wall-rock adjacent to lithium bearing pegmatites. It is in this case a metasomatic product or at least fluid - wall rock interaction.

This is a good example of replacement of minerals in the wall rock of pegmatites. This specimen formed as a result of lithium solutions emanting from the final stages of the pegmatite. The lithium intruded the amphibolite and converted the Hornblende to Holmquisite. London discusses wall rock alteration on pages 115-125 in the book "Pegmatites".