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)ySb2-x(O,OH,H2O)6-7 Cubic Bindheimite PbySb2-x(O,OH,H2O)6-7 Cubic Stetefeldtite AgySb2-x(O,OH,H2O)6-7 Cubic Partzite CuySb2-x(O,OH,H2O6-7 Cubic Tripuhyite Fe1-ySb1-x(O,OH)4 Tetragonal Byströmite Mg1-ySb2-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.