This sample of kurnakovite is displayed in the Smithsonian Museum of Natural History. Kurnakovite is a oxide mineral of boron (a borate) along with magnesium. It could be called magnesium borate. It has the composition MgB3O3(OH)5.5H2O. The sample at left is about 10 cm across and is from Boron open pit mine, Boron, California.