The mineral rambergite, hexagonal manganese sulfide, is found to crystalliz
e in the inverse wurtzite structure, i.e. the wurtzite type structure but w
ith the opposite absolute configuration, which can also be named anti-wurtz
ite. Rambergite was first found in the Garpenberg area, Dalarna, Sweden. Th
e sample used in this investigation contained approximately 5% iron, as det
ermined by microprobe analysis, giving the overall composition Mn1-x Fe-x S
, x similar or equal to 0.05.