Antimony discontinued. Antimony is resistant to attack by acids. Four allotropes of antimony are known: a stable metallic form and three metastable forms (explosive, black and yellow). Elemental antimony is a brittle, silver-white shiny metalloid. When slowly cooled, molten antimony crystallizes in a trigonal cell, isomorphic with the gray allotrope of arsenic. A rare explosive form of antimony can be formed from the electrolysis of antimony trichloride. When scratched with a sharp implement, an exothermic reaction occurs and white fumes are given off as metallic antimony forms; when rubbed with a pestle in a mortar, a strong detonation occurs. Black antimony
Sulfosalt minerals Sulfosalt minerals Sulfosalt minerals are those complex sulfide minerals with the general formula: ABS; where A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium; B usually represents semi-metal such as arsenic, antimony, bismuth, and rarely germanium, or metals like tin and rarely vanadium; and S is sulfur or rarely selenium or/and tellurium. The Strunz classification includes the sulfosalts in a "sulfides and sulfosalts" superclass. A group which have a similar appearing formulas are the sulfarsenides (for example cobaltite (Co,Fe)AsS). In sulfarsenides the arsenic substitutes for sulfur whereas in the sulfosalts the arsenic substitutes for