A mcgovernite-like mineral from the Kombat mine, Namibia, occurs with alleghanyite, calcite, and ribbeite. It has the approximate formula (Mn,Mg,Fe3+)273As˜123+As˜305+Si˜42O324-(OH)252. It is hexagonal, R32/c or R3c, with a = 8.224(4) and c = 204(5) Å. Comparison of its chemical composition with that of mcgovemite provides a tentative formula for mcgovernite-like minerals: (M2+,M3+)273As˜123+As˜305+Si˜42O324(OH)252, wherein M2+ = Mn,Mg,Zn, and M3+ = Fe3+,A1. The Kombat mine material differs from true mcgovemite in the absence of Zn, and the substitution of Al for most of the Fe3+.

Analytical data for two new occurrences of leucophoenicite, from the Kombat mine and from the Italian Alps, show that this mineral is Ca-bearing, does not contain essential Zn, and has not yet been found as the ideal end member, Mn7(SiO4)3(OH)2.

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