Tags: Chemical Substance, Mineral.
Staurolite is a red brown to black mostly opaque nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system has a Mohs hardness of 7 to 7.5 and the chemical formula: Fe2+2Al9O6(SiO4)4(OOH)2. Magnesium zinc and manganese substitute in the iron site and trivalent iron can substitute for aluminium.
