Boron compounds were relatively rarely used until the late 1800s when Francis Marion Smith's Pacific Coast Borax Company first popularized and produced them in volume at low cost. Sasso was the main source of European borax from 1827 to 1872, when American sources replaced it. The mineral was named sassolite, after Sasso Pisano in Italy.

In 1777, boric acid was recognized in the hot springs ( soffioni) near Florence, Italy, at which point it became known as sal sedativum, with ostensible medical benefits. Georgius Agricola, in around 1600 AD, reported the use of borax as a flux in metallurgy.

Marco Polo brought some glazes back to Italy in the 13th century. Some crude borax traveled westward, and was apparently mentioned by the alchemist Jabir ibn Hayyan around 700 AD. The word boron was coined from borax, the mineral from which it was isolated, by analogy with carbon, which boron resembles chemically.īorax in its mineral form (then known as tincal) first saw use as a glaze, beginning in China circa 300 AD. Although only traces are required, it is an essential plant nutrient. Boron-containing organic antibiotics are known. Borates have low toxicity in mammals (similar to table salt) but are more toxic to arthropods and are occasionally used as insecticides. Consensus on it as essential for mammalian life is lacking. The intersection of boron with biology is very small. Natural boron is composed of two stable isotopes, one of which ( boron-10) has a number of uses as a neutron-capturing agent. A few boron-containing organic pharmaceuticals are used or are in study. A small amount is used as a dopant in semiconductors, and reagent intermediates in the synthesis of organic fine chemicals. As sodium perborate, it is used as a bleach. Borosilicate glass is desired for its greater strength and thermal shock resistance than ordinary soda lime glass. The next leading use is in polymers and ceramics in high-strength, lightweight structural and heat-resistant materials. About half of all production consumed globally is an additive in fiberglass for insulation and structural materials. The primary use of the element itself is as boron filaments with applications similar to carbon fibers in some high-strength materials.īoron is primarily used in chemical compounds. Several allotropes exist: amorphous boron is a brown powder crystalline boron is silvery to black, extremely hard (about 9.5 on the Mohs scale), and a poor electrical conductor at room temperature. Industrially, the very pure element is produced with difficulty because of contamination by carbon or other elements that resist removal. The largest known deposits are in Turkey, the largest producer of boron minerals.Įlemental boron is a metalloid that is found in small amounts in meteoroids but chemically uncombined boron is not otherwise found naturally on Earth. These are mined industrially as evaporites, such as borax and kernite.

It is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. It constitutes about 0.001 percent by weight of Earth's crust. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride.īoron is synthesized entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Earth's crust. In its crystalline form it is a brittle, dark, lustrous metalloid in its amorphous form it is a brown powder. Boron is a chemical element with the symbol B and atomic number 5.

Boron natural abundance