Gaylussite is a rarely occurring mineral from the mineral class of carbonates ( and nitrates) [* ]. It crystallizes in the monoclinic crystal system with the chemical composition Na2Ca [ CO3 ] 2 • 5 H2O.
In nature Gaylussite usually comes in the form tafeliger to prismatic crystals or dipyramidaler before, which are either colorless or white, gray and yellowish in color.
Gaylussite melts before the blow torch and dissolved in water, Na2CO3 splits off.
Etymology and history
Was first found in 1826 Gaylussite named at Lagunillas / Mérida in Venezuela and described by Jean -Baptiste Boussingault ( 1802-1887 ), of the minerals by the well-known because of its gas laws French chemist and physicist Joseph Louis Gay -Lussac ( 1778-1850 ).
In the now outdated 8th edition of the classification of minerals according to Strunz the Gaylussite still belongs to the common mineral class of " carbonates, nitrates and borates " and then to the Department of " water -containing carbonates without foreign anions ", where he, with Baylissit, Chalkonatronit, Pirssonit soda, thermonatrite and Trona forms its own group.
After Extensive revisions to the Strunz'schen Mineral classification, among other things, the borates were spun off into its 9th edition and now form a separate class. The Gaylussite is, however, still the " water -containing carbonates without foreign anions " assigned, but these are precisely divided by type and size of the cations involved. The mineral is thus correspondingly in the subsection "With large cations ( alkali and alkaline earth carbonates ) ".
The commonly used in English-speaking classification of minerals according to Dana assigns the Gaylussite as the 8th edition of the Strunz'schen systematics in the common class of " carbonates, nitrates and borates " and there in the department of " water -containing carbonates of general formula A MB2 n ( XO3 ) p • x (H2O) and the overall molar ratio (m n): p> 1: 1 "
Modifications and varieties
As Thinolith a pseudomorph of calcite is called after Gaylussite.
Education and Locations
Gaylussite formed by sedimentation mainly in evaporites, but also in Tonschiefersedimenten of alkali lakes and is found there in paragenesis with various minerals such as aegirine, among other things, Northupit, Pectolite, Pirssonit, Shortite, thermonatrite, Trona and Villiaumit.
So far Gaylussite could be detected at nearly 40 sites (as of 2009), so in addition to its type locality Lagunillas in Venezuela, among others, still at Laguna Santa Maria (Salta ) in Argentina; Lake Chad in West Africa; on Chabyêr Çaka ( Zabuye Salt Lake ) in Tibet; in " Wadi el Natrun " in the Sketischen desert (Sahara, Africa ); in the Italian Tuscany; on alkaline " Amboseli lake " in the Kenyan Amboseli National Park; the Chicxulub crater in Mexico; in the Mongolian Gobi desert; on the Kola Peninsula in Russia; in Dolny Harmanec (low Herma network) in Slovakia; in the " salt pans crater " near Pretoria in South Africa; in the salt mine at Bex in Switzerland and in the U.S. regions of California, Nevada, Oregon, Washington and Wyoming.
Gaylussite crystallizes in the monoclinic space group C2 / c with lattice parameters a = 14.361 Å; b = 7.781 Å; c = 11.209 Å and β = 127.84 °, and four formula units per unit cell.