Glauberite - Encyclopedia

    Class : Sulfates, chromates, molybdates
    Subclass : Anhydrous sulfates
    Crystal system : Monoclinic
    Chemistry : Na2Ca(SO4)2
    Rarity : Quite common

Glauberite is a frequent mineral in salt deposits of marine or lake origin, associated with rock salt (halite); it is also found in fumaroles and in nitrate deposits in desert regions. This mineral owes its name to the German chemist and physicist Johann Rudolf Glauber (1604-1668) who gave his name to sodium sulfate (Glauber's salt), contained in large quantities in glauberite. The crystals show various facies : often flattened lozenges, sometimes prismatic or pyramidal, with the faces often striated parallel to their intersection ; it is also common in lamellar masses. Glauberite is often colorless to yellowish gray, sometimes brick red. Like gaylussite, it is commonly transformed into calcite. It is incidentally a sodium ore, and a mineral little known to collectors.

Glauberite in the World

Magnificent transparent crystals come from the salt marls of Villarubia de Santiago, near Toledo in Spain, and Stassfurt (Saxony-Anhalt, Germany). Glauberite is common in Californian salt lakes. It also sometimes forms pretty little crystals in the fumaroles of certain Italian volcanoes (Vulcano, Aeolian Islands, Italy).

Glauberite in France

In France, glauberite is present in the salt layers of Lorraine (Varangéville, France).

Twinning and special crystallization

Glauberite is a mineral that is commonly replaced by calcite.

Fakes and scams

No scam known for this mineral.

Hardness : 2.5 to 3
Density : 2.75 to 2.85
Fracture : Conchoidal
Trace : White

TP : Opaque to transparent
RI : 1.507 to 1.536
Birefringence : 0.022
Optical character : Biaxial -
Pleochroism : None
Fluorescence : White to blue

Solubility : Hydrochloric acid

Magnetism : None
Radioactivity : None