PYROSMALITE

    Class : Silicates
    Subclass : Phyllosilicates
    Crystal system : Trigonal
    Chemistry : (Fe,Mn)8Si6O15(OH,Cl)10
    Rarity : Uncommon

Pyrosmalite is a phyllosilicate which forms at the expense of manganese silicates in areas having undergone contact metamorphism. It is the dimorph of friedelite, which forms an isomorphic series with manganopyrosmalite, its manganiferous equivalent. Ferropyrosmalite is considered an iron-bearing variety of pyrosmalite and not a mineral in its own right. Its name comes from the Greek pûr (fire), odma (smell) and lithos (stone), because it gives off a strong chlorine odor when heated. Pyrosmalite forms typical hexagonal crystals, prismatic to tabular, with a common barrel facies, or leafy aggregates of pistachio green to green-brown color, rarely red-orange.


Main photo : Pyrosmalite from Nordmark Odal Field, Bergslagen, Sweden © Rock Currier

Pyrosmalite from Nordmark Odal Field, Bergslagen, Sweden © Rock Currier
Pyrosmalite and galena from Broken Hill, Australia © Kelly Nash
Pyrosmalite from Broken Hill, Australia © Judy Rowe
Pyrosmalite from Broken Hill, Australia © Eugene & Sharon Cisneros

Pyrosmalite in the World

The most beautiful pyrosmalite crystals come from the Swedish mines of Nordmark (7 cm crystals), and the Australian mines of Broken Hill, where pyrosmalite and manganopyrosmalite occur in 5 cm crystals and in metric-sized clusters.

Pyrosmalite in France

In France, pyrosmalite is present in metamorphosed manganese deposits in the Pyrenees (Adervielle, Mail-de-la-Pique) and at Combe Brémond (Alpes-de-Haute-Provence).

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 4 to 4.5
Density : 3.06 to 3.19
Fracture : Undetermined
Streak : White

TP : Translucent
RI : 1.631 to 1.680
Birefringence : 0.038 to 0.040
Optical character : Uniaxial -
Pleochroism : Visible
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None