Alchemy Alphabet: REGULUS (< Latin: ?kinglet, small king?) ? pure form of metal, refined from ore, obtained by smelting or reduction, end-product of metallic ore smelting (as opposed to impure ore ? formerly in The Middle Ages: metal was called The Regulus of the ore from which it was reduced); also: Regulus-producing process. Also oft.refers to: Regulus (without specification) ? mean.: Regulus of Antimony (metallic form of antimony or alloys thereof).