Sturmanite with Calcite

N'Chwaning II Mine, N'Chwaning mining area, Kuruman, Kalahari manganese field (KMF), Northern Cape Province  South Africa (1987)

Specimen size: 3.5 × 1.6 × 1.3 cm = 1.38” × 0.63” × 0.51”
Main crystal size: 3.5 × 1.4 cm = 1.38” × 0.55”