Primary anhydrite in Precambrian gneisses from the swakopmund district,South West Africa

Anhydrite occurs as a primary rock-forming mineral in late-Precambrian gneisses from the Rössing area, South West Africa. Studies on critical mineral associations in the area indicate that temperatures during metamorphism approached or exceeded 700° C. Textural relations in the anhydrite-bearing gneisses show that the mineral remained in equilibrium with its associated phases during metamorphism.