Amphibole asbestos

Amphibole asbestos (EN: amphibole asbestos; DE: Amphibol-Asbest; FR: amphibole-asbeste; ES: anfibol-asbesto; RU: амфибол-асбест) is the general name of the thin-fibrous minerals of the group of amphiboles, which are capable to endure, not changing, the high temperatures.

Unlike the chrysotile asbestos, it is not soluble or poorly soluble within acids. There have the greatest importance the crocidolite, amosite, anthophyllite, rezhikit (riebeckite?) (magnesium sio-arfvedsonite), rhodusite; there have the lesser importance the actinolite and tremolite. They also name the crocidolite asbestos, according to the characteristical blue colour, as blue asbestos. It represents itself as the parallel-fibrous variety of riebeckite, Na2Fe32+Fe23+[Si8O22](OH,F)2. The common length of the fibre is 2-30 millimetres (maximal one is 75 millimetres). It is not worse than chrysotile asbestos by the mechanical strength, but loses the constitutional water at 200-500 degrees Celsius, and its strength is decreased.

Amosite asbestos is the thin-fibrous variety of gedrite (Mg,Fe2+)6(Al,Fe3+)[(Si,Al)8O22](OH)2. Its colour is usually grayish-white, less often white and brown. There is characteristical the large length of the fibre (100-175 millimetres on average). The tensile tearing strength is 3 gigapascals; it decreases sharply during the deformation and especially during the heating.

Anthophyllite asbestos is the variety of anthophyllite (Mg,Fe2+)7[Si8O22](OH)2. It is usually found in the form of the radiating and bundled aggregates. The colour is yellowish-gray or brownish-gray, green, grayish-white. The fibres are usually short. Among the amphibole asbestos, it is most acid-resistant, and preserves this property even at the temperature of 900 degrees Celsius. Anthophyllite asbestos is also resistant with respect to alkali.

Rezhikit (riebeckite?) asbestos (magnesium sio-arfvedsonite), Na3Mg4Al[Si8O22](OH,F)2, and rhodusite asbestos (crossite), Na2(Mg,Fe2+)3(Al,Fe3+)2[Si8O22](OH,F)2, are often named light-blue. The length of the fibres of the rezhikit asbestos is 20-30 millimetres, sometimes 300 millimetres, of the rhodusite asbestos is approximately 2-7 millimetres. The average tensile tearing strength of the non-deformed fibres of the rezhikit asbestos is 3.4 gigapascals, of the rhodusite asbestos is 1.7 gigapascals. They possess the excellent acid-resistance and great sorption capacity.

Amphibole asbestos is found as the hydrothermal minerals, which are formed mainly at the medium, partly at the low (rhodusite asbestos) temperatures. Amphibole asbestos is used within the chemical, paper, food, and other industries as materials, which are heat-resistant, acid and alkali resistant, filtering, and resistant to the action of sea water.