Rickardite and the identical artificial compound Cu4-xTe2 have the C38-type (Cu2Sb) of structure. Tetragonal, P4/nmm; a=3.97, c = 6.11 kX; 2Cu in (a): 000,½½0 (2—x)Cu in (c): 0½z1, ½0z1 with z1, = 0.27 + 0.01; 2Te in (c) :0½z2, ½Oz2, with z2=0.715+ 0.005. The structure is grossly defective, with x nearly constant and equal to 1.2 or roughly 1. The formula Cu4Te3 hitherto given for rickardite and for the artificial compound should therefore be replaced by the cell formula or, for simplicity, by Cu3Te2. The variously blue colours of rickardite and other copper ores containing Cu11 is attributed to Cu atoms in the higher than normal valence state.

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