Stibnite or antimonite is sulfide metalloid mineral of antimony with chemical formula (Sb2 S 3 ). The color is shiny lead-gray tarnishing to black with massive, granular, radiating, and elongated crystals habits ( Fig. 1.50 ). The mineral contains 71.7% antimony in its natural purest form. Stibnite crystallizes in orthorhombic system, needle ...Web