Na₂B₄O₅(OH)₄.8H₂O

This sample of borax is displayed in the Smithsonian Museum of Natural History. Borax is an oxide mineral containing boron and sodium with the composition Na₂B₄O₅(OH)₄.8H₂O. The sample at left is about 6 cm across and is from Western borax mine, Boron, California. This is part of the legendary evaporite deposit in Death Valley, California. From 1883-89, 20-mule teams hauled 36.9 ton loads of borax out of Death Valley. The deposit began forming some 10,000 years ago from evaporation of a vast lake.