Small Cabinet, 6.9 x 4.9 x 1.1 cm
Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa

The rare mineral ettringite (Hydrated Calcium Aluminum Sulfate Hydroxide), closely related to sturmanite, is well-known in specimens from the Wessels locality. It forms as a precipitate from hydrothermal solutions. This is a plate of bright yellow, solid ettringite, crystallized on the surface with the typical nailhead-form crystals.