Morimotoite, Ca3TiFe2+Si3012, has been found in contaminated rocks which are considered to be a kind of endoskarn at Fuka, Bitchu-Cho, Okayama Prefecture, Japan. Morimotoite is derived from andradite, Ca3Fe3 § by the substitution Ti + Fe z+ = 2Fe 3 § It is associated with calcite, vesuvianite, grossular, wollastonite, hematite, prehnite, fluorapatite, perovskite, zircon, baddeleyite and calzirtite. It is cubic with space group Ia3d. The unit cell dimension a is 12.162(3) A. Its refractive index n is 1.995(2) and the density 3.75(2) g cm -3 (meas.), 3.80 g cm -3 (calc.). The Mohs' hardness is 7.5. Calculation of the analytical data on the basis of twelve oxygen atoms and eight cations shows that this mineral has a simplified chemical formula Ca3 (Ti,FeZ §247247 where Ti > Fe 2+ > 0.5. Morimotoite was synthesized at low oxygen fugacities, 650 and 700~ and 1 kbar total pressure.

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