Calcite

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

Specimen size: 4.7 × 3.1 × 3.1 cm = 1.85” × 1.22” × 1.22”
Main crystal size: 3.1 × 1.8 cm = 1.22” × 0.71”