Summary: The mineralogy of the antimony oxides and antimonates is summarized in table VI. Apart from the polylnorphs of Sb₂O₃, senarmontite Table VI. Mineralogy of the antimony oxides and antimonates Senarmontite Sb₂O₃ Cubic Valentinite Sb₂O₃ Orthorhombic Stibiconite (Sb³⁺, Ca)_ySb_2-x(O,OH,H₂O)_6-7 Cubic Bindheimite Pb_ySb_2-x(O,OH,H₂O)_6-7 Cubic Stetefeldtite Ag_ySb_2-x(O,OH,H₂O)_6-7 Cubic Partzite Cu_ySb_2-x(O,OH,H₂O_6-7 Cubic Tripuhyite Fe_1-ySb_1-x(O,OH)₄ Tetragonal Byströmite Mg_1-ySb_2-x(O,OH)₆ Tetragonal and valentinite, they fall into two structural groups, a cubic group with the pyrochlore structure and a tetragonal group with the trirutile structure. When the antimony is associated with large cations the pyrochlore structure is stable; with smaller cations the trirutile structure is the stable form. Defect lattices are usual in these minerals, resulting in great variability of chemical composition and in physical and optical properties within the individual species.