Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony. The name is derived from the Greek στίβι stibi through the Latin stibium as the former name for the mineral and the element antimony. Structure Stibnite has a structure similar to that of arsenic trisulfide, As2S3. The Sb(III) centers, which are pyramidal and three-coordinate, are linked via bent two-coordinate sulfide ions. However, some studies suggest that the actual coordination polyhedra of antimony are SbS7, with (3+4) coordination at the M1 site and (5+2) at the M2 site. Some of the secondary bonds impart cohesion and are connected with packing. Stibnite is grey when fresh, but can turn superficially black due to oxidation in air. Properties The melting point of Sb2S3 is 823 K (550 °C; 1,022 °F). The band gap is 1.88 eV at room temperature and it is a photoconductor...