Purpurite
Purpurite is a manganese phosphate mineral with the formula MnPO4, with varying amounts of iron depending upon its source. It occurs in color ranges from brownish black via purple and violet to dark red. Purpurite forms a series with the iron-bearing endmember heterosite, FePO4. See also
Manganese violet

References 

Manganese(III) minerals
Iron(III) minerals
Phosphate minerals
Orthorhombic minerals
Minerals in space group 53