Holmquistite - Encyclopedia

    Class : Silicates
    Subclass : Inosilicates
    Crystal system : Orthorhombic
    Chemistry : Li2Mg3Al2Si8O22(OH)2
    Rarity : Uncommon


Holmquistite is a lithium amphibole that forms by metasomatic replacement at the contact between lithium pegmatites and basic rocks. It is a dimorph of clinoholmquistite which forms two series with ferro-holmquistite on the one hand and magnetio-holmquistite on the other. It was named in honor of the Swedish petrologist Johan Holmquist. Holmquistite forms prismatic to acicular crystals that can measure 10 cm, dark purple to black in color, rarely sky blue. It commonly accompanies spodumene, tourmaline and biotite.

Main photo : Holmquistite from Brandrücken, Austria © Christian Auer

Holmquistite in the World

The largest known crystals of holmquistite are assembled in radiated groups of 15 cm and come from the gigantic lithium pegmatite of Greenbushes in Western Australia. Beautiful crystals have been discovered in the pegmatites of Tanco (Manitoba, Canada) and üto (Sweden). Holmquistite is also present on the walls of the famous American lithic pegmatites of South Dakota (Keystone) and North Carolina (Stony Point, Foote, near Kings Mountain).

Holmquistite in France

This mineral is not present in the French underground.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.



Hardness : 5 to 6
Density : 2.95 to 3.13
Fracture : Undeterminated
Streak : White to sky blue


TP : Translucent to transparent
RI : 1.613 to 1.666
Birefringence : 0.033 to 0.041
Optical character : Biaxial -
Pleochroism : Strong
Fluorescence : None


Solubility : Insoluble

Magnetism : NoneRadioactivity : None

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