Cobalt Orthosilicate, Co₂SiO₄

Cobalt Orthosilicate, Co₂SiO₄, is obtained by heating to bright redness a mixture of amorphous silica, and the chloride and oxide of cobalt. Excess of silica is removed by treatment with concentrated soda solution, the residue consisting of the orthosilicate in the form of a violet crystalline powder. The crystals are isomorphous with peridote; density 4.63. They are decomposed by hydrochloric acid.