Boron

Amorphous (non-crystalline) boron is used in pyrotechnics to provide a distinctive green color and in rockets as an igniter.   The pentahydrate, Na₂B₄O₇ • 5H₂O is used in the manufacture of fiberglass insulation and sodium perborate bleach.   Boric acid is important in textile products and in cellulose insulation as a fire retardant.   Borax, Na₂B₄O₇ • 10H₂O, has many industrial uses: ceramic glaze production, glassmaking, a soldering and welding flux, water softener, disinfectant, and in fertilizer production.   Boron compounds are used in the manufacture of borosilicate glass.   The isotope Boron-10 is used as a control in nuclear reactors.   Boron nitride is used to make abrasives as hard as diamond. ^{Lide 4-5}

Boron is essential to plant life.   Boron is integral to a plant's reproductive cycle, controlling flowering, pollen production, germination, seed and fruit development, cell division, water relationships and the movement of hormones.   It also acts as a fuel pump, aiding the transmission of sugars from older leaves to new growth areas and root systems. ^{Borax n.p.}   Boron is necessary for cell wall formation, membrane integrity and calcium uptake.   Boron must be available throughout the life of the plant, since it is not translocated and is easily leached from soils.   Deficiencies kill terminal buds, leaving a rosette effect on the plant and leaves are thick, curled and brittle.   Fruits, tubers and roots are discolored, cracked and flecked with brown spots. ^{Morgan n.p.}

Boron compounds were known to the ancients, but Sir William Humphrey, Gay-Lussac and Thenard discovered the element in 1808.   Boron is found in volcanic spring waters and as borates in borax and colemanite.   Ores containing boron are kernite (rasorite) and tincalconite (tincal).   Crystalline boron is prepared by the vapor phase reduction of boron trichlorid or tribromide with hydrogen on electrically heated filaments.   Amorphous boron is obtained by heating the trioxide with magnesium powder. ^{Lide 4-6}