Global Borate Supplier of Choice Rio Tinto Borax operates Californias largest open pit mine in Boron, California - one of the richest borate deposits on the planet. The company supplies nearly half the world......Global Borate Supplier of Choice Rio Tinto Borax operates Californias largest open pit mine in Boron, California - one of the richest borate deposits on the planet. The company supplies nearly half the worlds demand for refined borates, minerals essential to life and modern living. Borax traces its roots to Californias Death Valley, where borate deposits were discovered in 1872. The twenty mule teams Borax used to haul ore out of the remote desert live on as a symbol of the companys commitment to innovation. Today, Borax is acknowledged as the world leader in borate technology, research and development. Technical support for customers, product quality, and supply reliability are the pillars of our commercial commitment. We are also committed to ensuring that our practices and products are socially, environmentally and economically sustainable. Borax is a member of the Rio Tinto group.