TSCHERMIGITE

    Class : Sulfates, chromates, molybdates
    Subclass : Hydrated sulfates
    Crystal system : Cubic
    Chemistry : (NH4)Al(SO4)2 12H2O
    Rarity : Uncommon

Tschermigite, also called "ammoniacal alum", is an aluminum and ammonium sulfate from coal mines, burning coal mines and burnt anthracite layers, also present in some fumarolic deposits. Its name comes from its locality of discovery : Tschermig (Czech Republic). Tschermigite occurs in efflorescence and in colorless or white fibrous columnar masses. Octahedral crystals are rare.

Main photo : Tschermigite from Pécs-Vasas, Hungary © Vincent Bourgoin

Tschermigite in the World

Tschermigite is found in efflorescence and in crystalline masses in several fumarolic sites in California (Sulphur Bank, The Geysers...). It is abundant in the oil shales of Wamsutter (Wyoming), in the coal mines of Tschermig (Czech Republic) and in levels of consumed anthracite in Pennsylvania. It is also found in the fumaroles of Italy, in Pozzuoli and at Etna. The most beautiful crystals are infra-millimeter and come from the old coal mine of Pécs-Vasas (Hungary).

Right photo : Tschermigite from Pécs-Vasas, Hungary © Stephan Wolfsried

Tschermigite in France

In France, tschermigite is reported in Décazeville (Aveyron), Avion (Pas-de-Calais) and the Grotte aux Serpents (Savoie).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 1.5 to 2
Density : 1.645
Fracture : Conchoidal
Streak : White

TP : Transparent
RI : 1.458
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Water

Magnetism : NoneRadioactivity : None