The humite group can be represented as a polysomatic series constructed from slabs of the olivine Mg2SiO4 and norbergite Mg3SiO4(F,OH)2 structures. Here we report the crystal structures of two new calcium-silicate minerals of the humite group from skarned carbonate xenoliths at the Verkhn’echegemskiy volcanic area in Kabardino-Balkaria, North Caucasus, Russia. One, is the fluorine-dominant analogue of reinhardbraunsite with polysomatic notation (ON) and the other is Ca7(SiO4)3(OH,F)2 (Ca-analogue of humite) with the polysomatic notation (O2N).
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