MILARITE

    Class : Silicates
    Subclass : Cyclosilicates
    Crystal system : Hexagonal
    Chemistry : (K,Na)Ca2AlBe2Si12O30 H2O
    Rarity : Rare to uncommon

Milarite is a complex silicate of beryllium, aluminum, calcium and potassium, which is found in pegmatites and Alpine clefts. Although discovered in Val Giuf in Switzerland, this mineral bears the name of the neighboring deposit of Val Milar in which it is also present. Milarite always appears crystallized, in elongated hexagonal prisms, sometimes in barrels, colorless or yellowish, green, sometimes purplish in color. It is very occasionally cut as a fine gemstone.

Main photo : Milarite from Val Giuv, Tujetsch, Switzerland © Dan Weinrich

Milarite and chlorite from Val Giuv, Tujetsch, Switzerland © Martin Gruell
Milarite on albite from Guanajuato, Mexico © Rock Currier
Milarite from Jaguaraçu, Minas Gerais, Brazil © Martin Slama
Milarite from Rössing, Namibia © Martin Slama

Milarite in the World

Milarite from the Swiss Alpine clefts (where it was discovered) constitutes particularly aesthetic associations, in 3 cm crystals accompanying axinite, adularia or smoky quartz. The most beautiful crystals, sometimes colorless, come from Val Giuv, the Fiescher glacier and Val Stern which provided the largest known specimens. Superb greenish to green-yellow crystals measuring up to 3 cm on adularia were discovered in the pegmatites of Valenciana (Guanajuato, Mexico). Pegmatites from Jaguaraçu (Minas Gerais, Brazil) produced 3 cm green-yellow zoned prismatic crystals, considered the best in the world. Excellent gem samples also come from the Rössing pegmatites (Namibia).

Milarite in France

Milarite is not known in the French underground.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 6
Density : 2.46 to 2.61
Fracture : Irregular to conchoidal
Streak : White

TP : Transparent to translucent
RI : 1.532 to 1.548
Birefringence : 0.003
Optical character : Uniaxial -
Pleochroism : None
Fluorescence : None

Solubility : Hydrofluoric acid

Magnetism : NoneRadioactivity : None

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