The major ores of boron are a small number of borate (boron oxide) minerals, including ulexite (NaCaB5O9.8H2O), borax (Na2B4O5(OH)4.8H2O), colemanite (Ca2B6O11.5H2O) and kernite (Na2B4O6(OH)2.3H2O). These minerals form when boron-bearing waters percolate into inland desert lakes and evaporate, leaving layers of borates, chlorides, and sulfates. These minerals are referred to as evaporite minerals. Very large deposits of evaporite boron minerals are found in the United States (especially California), Turkey, Chile and Argentina. Less-important deposits occur in Iran (formerly called Persia), and elsewhere. 

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Kernite and borex are important ores of boron