The Probert Encyclopaedia of Rocks & Minerals

REALGAR

Realgar is a sulphide of arsenic found in veins of lead, silver, and gold ores associated with arsenic minerals and stibnite and also occurs as a deposit from hot springs. When mixed with saltpetre and burned it gives a bright white light and was formerly used in fireworks to provide colour. It has the formulae AsS and a relative hardness of 2.
Research Realgar