Цирконий силикат

Описание

Zircon (ZrSiO4) is an accessory nesosilicate mineral found in granites and, due to its high Mohs hardness of 7.5 and chemical inertness, it concentrates in the weathering products of mother igneous rocks such as in alluvial placer deposits and beach sands. Because of its chemical inertness and high melting point, zircon is wetted less easily by molten metal, producing smoother surfaces on iron, high alloy steel, aluminum, and bronze casting.

Химические свойства

Zirconium silicate is a colorless tetragonal crystals (when pure); presence of impurities forms various colors; density 4.56 g/cm3; hardness 7.5 Mohs; dissociates to ZrO2 and SiO2 above 1,540°C; melts at 2,550°C; insoluble in water, acids, aqua regia, and alkalies; inert in most chemicals. Zirconium silicate is used as an additive to glass, in ceramic tiles, in ultrafiltration membranes, and as a dental abrasive.

Использование

Zirconium silicate (ZrSiO4) is one form of the mineral whose crystals when polished are known as cubic zircons, which resemble diamond gemstones.

Подготовка

Zirconium silicate occurs in nature as mineral zircon. Ore is mined from natural deposits and concentrated by various techniques (See Zirconium, Recovery). It is separated from sand by electrostatic and electromagnetic methods. Also, the compound can be made by fusion of SiO2 and ZrO2 in an arc furnace, or by reacting a zirconium salt with sodium silicate in aqueous solution.

Определение

Zirconium silicate is a naturally occurring silicateof zirconium, ZrSiO4, used as a gemstone.The colour depends in smallamounts of other metals and may bered, brown, yellow, or green. Redgem-quality zircon is sometimescalled jacinth; gem-quality zirconswith other colours are called jargoons.There is also a naturally occurringcolourless variety. Zircongems can be given other colours, ormade colourless, by heat treatment.The colourless varieties (either naturalor treated) are sometimes calledMatura diamonds (after Matura in SriLanka). The name 'zircon' is often erroneouslyapplied to a synthetic formof the oxide cubic zircona, which isused as a diamond substitute.