This sample of kernite is displayed in the Smithsonian Museum of Natural History. Kernite is a oxide mineral of boron (a borate) with sodium. It has the composition Na2B4O6(OH)2.3H2O. The sample at left is about 8 x 30 cm and is from Kern County, California.
Sodium borates such as kernite with borax (sodium tetraborate decahydrate, Na2B4O7. 10H2O) and colemanite (calcium hexaborate pentahydrate, Ca2B6O11. 5H2O) form vast deposits of boron in California .