SELLAITE

SELLAITE, a mineral of the fluorides class. Crystals are columnar, from long prismatic ones to needle‑like. Aggregates are fine‑grained, in the form of crystalline crusts and individual grains. The color is white, with glassy luster. It is formed in salt‑bearing, dolomite‑anhydrite, and fumarolic sediments and hydrothermal deposits. Abroad, S. (mainly synthetical) is used in optical production. In the Urals, S. was first expored in Bashkortostan at the Suranskoye Deposit of fluorspar, where it builds up the fluorite‑preceding veins with the formation temperature of 105—130°С; it is assigned a separate grade, its acknowledged reserves of category C1 amount to 19.08 thous. t.