Search results

...lly as [[corundum]] ([[ruby|rubies]] and [[sapphire]]s), [[emery (mineral)|emery]], and is used in [[glass]] making. Synthetic [[ruby]] and [[sapphire]] are ...ure of the reduction cells is around 950 to 980 °C. Cryolite is found as a mineral in Greenland, but in industrial use it has been replaced by a synthetic sub