Cobalt Sesquitelluride, Co₂Te₃

Cobalt Sesquitelluride is obtained in the hydrated form, Co₂Te₃.4H₂O, as a black precipitate when a solution of sodium telluride is added to one of cobalt acetate in dilute aqueous acetic acid. Hydrochloric and sulphuric acids are without action upon it, but nitric acid effects its oxidation. At 200° C. it loses water, and at red heat, tellurium; if heated till no further loss in weight occurs, Cobalt Monotelluride, CoTe, is obtained as a grey, crystalline substance of metallic lustre.