Characteristics: Nonmetallic element, black, hard solid; brown, amorphous powder; crystals. Highly reactive. Soluble in concentrated nitric acid and sulfuric acid; insoluble in water, alcohol, and ether. High neutron absorption capacity. Low toxicity. Amphoteric. A plantmicronutrient. Mohs hardness 9.3.
Derivation: (a) by heating boric oxide with powdered magnesium or aluminum; (b) by vaporphase reduction of boron trichloride hydrogen over hot filaments (800-2000 oC); (c) electrolysis of fused salts.
Hazard: Boron powder may react violently with halogenated carbons. Reacts exothermally with metals over 900 oC; explodes with hydrogen iodide.