Albite

ALBITE (from the Latin word "albus", which means white, according to the colour * EN: albite; DE: Albit; FR: albite; ES: albita; RU: альбит) is the rock-forming mineral of the feldspars family.

Albite is the member of the isomorphous series of the plagioclases and K-Na feldspars. There in the plagioclase series belong to the albites the extreme acidic members, which are containing 90-100% of Na[AlS3O8] and up to 10% of Ca[Al2Si2O8]. The complete miscibility within the series of the K-Na feldspars (K, Na)[AlSi3O8] is achieved at the high temperatures; the cooling leads to the disintegration of the solid solution with the forming of the perthites.

They distinguish, according to the distribution of Al in the crystal lattice, the completely disordered high temperature monoclinic albite (may be found in the certain lavas) and the ordered low-temperature triclinic albite (is widespread in the rocks). The crystals of the albite are rare; there are more common the granular, coarse and fine tabular, often saccharoidal aggregates, grains of the elongated tabular (lath-shaped) or irregular isometric shape.

The cleavelandite is the tabular albite of the granitic pegmatites, which is forming the spherical rosettes. There are characteristic for the albite the polysynthetic twins, more often according to the albite law. The albite is usually of the white colour, the cleavelandite is yellowish. It is coloured by the admixtures into the yellowish and reddish colours. The lustre is glassy. The hardness is 6-6.5; it is brittle. The density is 2600-2630 kilograms per cubic metre.

Albite is the typical mineral of the rare metal granitic pegmatites, tantalum-bearing granites (including the amazonitic ones), nephelinic and alkaline syenites, fenites, greenstone effusive rocks (especially spilites, keratophyres), green schists, albitophyres. Albite is completely formed of the rocks of the metasomatic origin, namely, of the so-called albitites, which are often bearing the rare metallic mineralization. The albitization has widely manifested itself in the certain pegmatites, granites, alkaline rocks, fenites, and also in the rocks of the volcanic regions. The authigenic albite may be found also in the sedimentary rocks. They use it in the glass, ceramic, abrasive industries. The major method of the benefication of albite is the flotation with the preliminary extraction of the micas and quartz from the ores. The collectors are: the cationic ones in the acidic environment, the mixture of the petroleum oils, the fatty acids in the alkaline environment; the activators are: the cations of the alkaline earth and heavy metals, HF; the depressors are: the sodium sulfide, alkali. During the gravitational benefication of the ores of the rare-metallic pegmatites, and of the granites, the albite goes into the tailings together with quartz and the part of the potassic feldspar.