Light micrograph of a section of silicon carbide, classed as an engineering ceramic and known to the geologist as the mineral carborundum. Like all ceramics, it is an extremely stable material with high- temperature strength and good resistance to corrosion. Silicon carbide has several useful properties, including electrical conductivity. It is used for furnace linings and electrical heating elements where high temperatures are reached. The jeweller uses it to polish gemstones. This specimen is from a refractory brick of the type used to line the walls of a metal-smelting furnace. Magnification unknown. Microcosmos p.156 fig.8.14.