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ABSTRACT. Electron probe microanalyses carried out on thirty areas of lithiophorite (A1,Li)MnO2(OH)z from five Australian localities indicate wide variations in its Ni, Co, Cu, and Zn content. The concentration of these elements varies inversely with the alumina content, though there is a marked change in their concentration at 18 ~o alumina, suggesting the existence of two varieties of lithiophorite with differing concentration of transition elements. EPMA line scans also indicate definite changes in Co content in lithiophorite grains less than 0.2 mm in dimension. The variations in alumina and transition elements may be explained if lithiophorite is considered to be an irregular mixed-layer-lattice intergrowth of pure lithiophorite with members of the recently discovered asbolane-type minerals.

Select area electron diffraction and microanalysis of the optically dark component of a ferromanganese nodule from the South East Indian Ocean Manganese Field indicate that this is composed of a random stratification of crystallites of vernadite MnO2. (R2O, RO, R2O3)x. yH2O, where R represents elements such as K, Ba, Na, Ca, Mg, and a disordered hydrated iron oxide, possibly ferrihydrite 5Fe2, O3. 9H2O or feroxyhyte δ′-FeOOH. Whether the dark component is an irregular mixed-layer hybrid mineral or a layered accumulation resulting from epitaxy of the above phases is uncertain.

Variations in the cholesterol bile pigment and calcium salts contents of gallstones formed in gallbladder and in bile ducts with the degree of associated obstruction. Ann. Surff. 109, 161-86.