Sturmanite with Calcite

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

Specimen size: 3.6 × 3 × 2.6 cm = 1.42” × 1.18” × 1.02”
Main crystal size: 1.3 × 0.9 cm = 0.51” × 0.35”