Boron is named from the Arabic burah. Boron compounds have been known for thousands of years, but the element was not discovered until 1808. The element is not found free in nature, but occurs as orthoboric acid usually in certain volcanic spring waters and as borates in borax and colemanite. By far the most important source of boron is the mineral rasorite, also known as kernite, found in the Mojave Desert of California. Extensive borax deposits are also found in Turkey. Boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. The most important compounds of boron are boric, or boracic, acid, widely used as a mild antiseptic, and borax which serves as a cleansing flux for welding and as a water softener in washing powders.