1) Hexagonal mineral 2) Manganese mineral 
Rambergite is a manganese sulfide mineral with formula MnS. It has been found in anoxic marine sediments, rich in organic matter of the Gotland Deep, Baltic Sea and also in skarn in the Garpenberg area, Dalarna, Sweden. It was named after the mineralogist, Hans Ramberg (1917-1998). It is closely related to Hauerite. ...