Glauberite

Glauberite is a widespread but only locally frequent occurring mineral from the mineral class of sulfates, selenates, tellurates, chromates, molybdates and tungstates. It crystallizes in the monoclinic crystal system with the chemical composition Na2Ca (SO4) 2 and forms up to ten centimeters wide, gray or colorless, tabular, prismatic crystals or dipyramidal.

Special Features

Since sodium sulfate is water soluble, also glauberite is partially soluble in water, while other minerals such as gypsum are deposited. This also occurs in moist air, therefore the mineral is not stable at this and form efflorescence and crusts of gypsum.

Etymology and history

Glauberite was first found in 1808 by M. Dumeril in the type locality near Villarrubia de Santiago in the Spanish province of Castilla -La Mancha and described by Alexandre Brongniart. He named the mineral after Johann Rudolph Glauber, who discovered the glauberite similar sodium sulfate ( Glauber's salt) and described.

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the glauberite belongs to the department of " water clear Sulfate without foreign anions ." The new Strunz'sche Mineral classification divided here, however, precisely according to the size of the cations involved, and therefore the mineral is now in accordance with the subdivision " Mitausschließlich large cations " where he is the unnamed group 7.AD.25 the only member.

The commonly used in English-speaking classification of minerals according to Dana assigns the glauberite also in the class of sulfates, but there in the department of " water clear acids and sulfates with different formulas ," where he also forms the unnamed group 28.4.2 the only member.

Education and Locations

Glauberite formed under dry conditions in evaporites, sediments and salt lakes. Even as a precipitate by sublimation in fumaroles, in caves of basaltic lava and nitrate deposits to glauberite can form. It is associated with halite in evaporites, polyhalite, anhydrite, gypsum, thenardite and mirabilite; in fumaroles with thenardite and sassolite; in nitrate deposits with thenardite and Blödite.

There are currently (as of May 2010) 84 localities of Glauberits known. In addition to the type locality Douglas Hall include at Westeregeln in Saxony -Anhalt ( Germany ), Hallstatt in Austria, Varangéville in France, Antofagasta in Chile, the Great Salt Lake and other locations in the United States, Gypsumville in Canada, Lochiel, South Australia, Vulcano in Italy and Surtsey in Iceland.

Crystal structure

Glauberite crystallizes in the monoclinic crystal system, space group C2 / c with lattice parameters a = 10.129 Å; b = 8.306 Å; c = 8.533 Å and 112.19 ° β =, and four formula units per unit cell.

Use

Glauberite used locally as the basis for the production of sodium sulfate. Earlier it was mined for the Sodagewinnung.