William Valdez, age 10, of Jamestown, N.Y., for his question:
WHERE DOES BORAX COME FROM?
Borax is an important chemical compound of the element boron. Most of the world's supply comes from Southern California. It has been estimated that there is more than a 100 year supply of borax in just one of California's many mines alone.
Borax is a soft, white, many sided crystal that dissolves readily in water. Borax is well known for its use in washing powders, water softeners and soaps. It is also used in medicines and for ointments and eye washes.
Manufacturers mix borax with clay and other substances to make enamel glazes for sinks, stoves, refrigerators and metal tiles. Potters use borax to add strength to their products and to make a hard glaze for dishes.
Glassmakers mix borax with sand so that it will melt easily and give strong, brilliant glass. Glass cooking utensils and thermometers are made from glass that contains borax.
Borax is also sometimes used as a food preservative and in the textile industries, in tanning leather and in making paper.
In California, borax may be taken from open pit mines in the Mojave Desert. In these, miners strip away the covering ground to expose the borax bed. Workers use dynamite to blast loose the solid borax.
The large chunks of borax are then crushed and dissolved. This solution goes through many purification steps until borax crystals are obtained.
Borax is also obtained from "dry" or "bitter" lakes. The brine, which contains many salts other than borax, is pumped from the lake into containers. The solution is allowed to stand in vats to separate the borax from the heavier salts, which sink to the bottom. The remaining brine crystallizes and the borax is refined.
Borax crystals will clump together if they are exposed to moist air.
When borax crystals are heated in a loop of platinum wire, they swell because the water in them evaporates. When all of the water is gone, a clear, glassy liquid remains. This liquid combines with many metallic oxides to produce "borax beads" of various colors.
In mineral and chemical analyses, the borax beads are used to detect the presence of certain metals. If cobalt is present, a dark blue bead appears; for copper, a light blue one; for nickel, brown; and for manganese, amethyst.
Kernite is 75 percent pure sodium borate. It was discovered in the Mojave Desert in 1926, and is a major source of commercial borax. It is dissolved in water, and, after the impurities are filtered off, it is allowed to recrystallize. This is a cheap and easy way to produce borax.
Tibet is said to have been the first important source of borax. Since the 1920s, the United States has produced most of the world's borax.
Borax deposits were discovered in California's Death Valley in 1873. Actual mining started in the early 1880s and famous 20 mule teams hauled the borax out of the valley.