Boron is a low-abundance metalloid element used in semiconductor doping.
Core Principles & Analysis
Borax had been used for centuries before Gay-Lussac and Thenard in Paris and Humphry Davy in London independently isolated impure boron in 1808.
This hard, black metalloid forms unusual electron-deficient bonds, and its boron-10 isotope is a strong absorber of neutrons.
Boron gives borosilicate glass like Pyrex its thermal shock resistance, hardens boron carbide armor, and serves in neutron-absorbing control rods for nuclear reactors.