ANTIMONITE (from the Late Latin "antimonium" (antimony)), stibnite (EN: antimonite, stibnite; DE: Antimonit, Antimongla nz; FR: antimonite, antimoine sulfure; ES: antimonita, estibnita; RU: антимонит) is the mineral of the class of sulphides, namely, the Sb2S3; it is the major source for the obtainment of antimony. It contains 71.45-71.83% of Sb, 28.42-28.90% of S; the admixtures are: As, Hg, Ag, Au, Pb, Bi, Fe, Cu. It crystallizes into the orthorhombic crystal systems; there are situated within the basis of the crystal structure the chains of the Sb4S6. It forms prismatic needle-shaped crystals with characteristic hatching along the faces, and also fan-shaped intergrowths, interweaved-fibrous and granular aggregates. The colour is lead-gray, the lustre is metallic. The hardness is 2-2.5. The density is 4500-4600 kilograms per cubic metre. It has strong double reflectivity and anisotropy; the temperature of melting is 546 degrees Celsius. It is slightly soluble within HCl.

According to its origin, it is the low-temperature, hydrothermal one; it also forms itself within the depositions of the hot water sources. It may be found, besides the antimony deposits proper, within many antimony-mercury deposits, and also in small quantities within the gold-quartz veins, within the deposits of realgar, and orpiment, and within the lead-zinc ones. It is beneficiated mainly with the help of flotation. The sorbents are xanthates, dithiophosphates, thiocarbanilides within the Na2CO3 environment. The activators are ions of Cu, Pb. It is flotated within the acidic environment with foamers and oils exclusively. See also the "Antimony ores" article.