Geophagia by mountain gorillas (Gorilla gorilla beringei) in the Virunga Mountains, Rwanda

Mountain gorillas (Gorilla gorilla beringei) occasionally eat material from weathered regolith (subsoil) sediments in the Virunga Mountains of northwestern Rwanda. The possible nutritional significance of this behaviour has been investigated by analyzing the geochemistry, primary mineral composition, and clay content of several regolith and surface soil (paleosol) samples. Iron, Na, and Br content may be important in geophagy, and clay present in the soil may also have nutritional importance.