Antimony sulfide contained in an antimony sulfide bearing ore, such as stibnite, is converted to high purity antimony trichloride by reacting the antimony sulfide bearing ore with a source of chlorine to form high purity antimony trichloride and sulfur or hydrogen sulfide as separable by-products. The high purity antimony trichloride may be hydrolyzed to form high purity antimony oxide