Composition of some urinary calculi of ruminants in Western Australia.

Forty ruminant urinary calculi, selected as being essentially inorganic and mainly obtained from sheep grazing in the drier wheatbelt areas of Western Australia, were examined by optical and X-ray diffraction techniques. Four mineral types-silica (SiO2-nH2O), weddellite (CaC2O4-2H2O), calcite (CaCO3) and aragonite (CaCO3)--were found. These minerals were present respectively in 30, 17, 13 and 1 of the 40 calculi examined and were the sole component in 12, 0, 7, and 0 calculi. One calculus was found to be composed of organic material which was subsequently shown to consist mainly of 4'-O methyl equol (4'-methoxy-7-isoflavanol, C16H16O3) with a small amount of equol and a trace of formononetin. This is the first report of a calculus of this composition. Determinative data useful for identification of 4'o-methyl equol, equol and a related substance are presented in an appendix.