Summary: Chemical analyses, optical properties, and specific gravities are presented for nine axinites. A reciprocal substitution relationship is demonstrated between Mg and Mn²⁺, and a linear variation diagram is constructed between refractive indices and the (Fe²⁺+Fe³⁺+Mn²⁺+Ti) ions calculated on the basis of 16(O,OH). The composition of these axinites is independent of the composition of their host rocks; their colour appears to be independent of the Fe²⁺/Mn²⁺ ratio for the range of iron and manganese values of the specimens investigated.