Rus
 

Stone, minerals and semiprecious of the world stone
Spar (silicates): Sodalite -->rus

   Diagnostic cart.

   Na8 Cl2 (Al Si O4)6
   Crystal structure cube
   Hardness on the Mohs scale 5-6
   Specific unit weight mass 2,27-2,33
   Cleavage perfect absolute
   Fracture, break padman
   Colors colourless, polycoloured (multicoloured)
   Colors in powder triturate white
   Glance (glitter, glare) from glass to fat

   The name is related to composition of mineral (British natrium sodium is natrium sodium). Sodalite is various tones of dark blue color - from a cornflower blue to violet-blue and quite often intersects the white veins of Calcite. Glance (glitter, glare) on the planes of cleavage of glassy, in a fracture - fat. A blue, grey, yellow, or colourless mineral consisting of sodium aluminium silicate and sodium chloride in cubic crystalline form. It occurs in basic igneous rocks. Formula: Na4Al3Si3O12Cl, Soda + Lite.

   Very rarely be found as rhombo-dodecahedral crystals, more frequent is as wrong grains or dense aggregates. It can be colourless, sometimes light-blue, and also greyish-white with a rose raid, light-yellow or greenish. Has glassy brilliance with a tendency to fat on the surfaces of cleavage.

   Chemical composition (chemistry, compound). Oxide of natrium sodium (Na2O) 25,5%, oxide of aluminium (Al2O3) 31,7%, silex (SiO2) 37,1%, chlorine (Sl) 7,3%. A mineral is aluminum silicate of natrium sodium. Form of crystals. Rombododekaedry. Class of symmetry. Geksatetraedricheskiy - 43. Cleavage. Clear to on (110). Aggregates. Grainy.

   Diagnostic indication.

   In flame of candle melt fuse, giving colourless glass and painting flame in yellow, gold color in compound with the presence of natrium sodium. Muriatic acid fully decomposes him with the selection of jelly-like silica. Sodalite changes easily, often deputized a fibred-radiant natrolite which quite often is accompanied other zeolite and two-bits of cancrinite, sericite, diaspore, kaolin and Calcite. Dark blue, grey, white, rather yellow, colourless.

   Easily to entangle Sodalite with Lazurite: inclusion Pyrite, constituents so characteristic feature of Lapis lazuli (Lazurite), meet also and in Sodalite, but far rarer. Reliable diagnostic signs at that rate are a different closeness of minerals and perfect absolute cleavage at Sodalite. Sodalite is alike also on Azurite, Dumorterite, lazulite. Colors: from a cornflower blue to navy blue.

   Origin provenance genesis.

   Often present as accessory and rockforming mineral in alkaline orthorocks, poor a silica. Thus he is associated with leucite and nephelite. Now and then Sodalite be found in contact deposit-metamorphized granular limestone, marble.


Sodalite. Kochabamba, Bolivia. ~10 sm . A photo: © A.A. Evseev.

   Deposit minefield mine and use.

   Deposit minefield mine field occurrence subsoil is timed to the magmatic alkaline rocks. Most considerable from them are in Brazil (Baiya), other - in Canada (. Ontario), India, Republic of South Africa, USA. The rich concentrations of Sodalite are set in syenitic rocks in a number of areas of the Canadian provinces of Ontario, Quebec and Britannic Colombia. A mineral is also in the state Arkansas (USA), in bolivian Andes, on Ural (Russia, CIS), in Portugal, Zimbabwe and Greenland. In Italy be found in the effusive rocks of Flegreyskikh of the fields near Naples, in geode of volcanic bombs of Vesuvius and in the products of volcanic eruptions of trachytic nature in Monti-Chimini in the province of Viterbo. If Sodalite forms dense and homogeneously painted the masses, it is obtained for making of statuettes, necklace, bangles and other hand-made articles. For jeweller aims dense aggregates are suitable only. Cabochon make out of them, beads, use in a rock-cutting art.


Sodalite. "Baiya", Brazil. A photo: © A.A. Evseev.