Chromium - 24Cr: historical information
In the mid 18th century analysis of Siberian "red lead" (PbCrO4, crocoite) from Siberia showed that it contained quite a lot of lead, but also a further material. This was eventually identified as chromium oxide. Chromium oxide was discovered in 1797 by Louis-Nicholas Vauquelin, who prepared the metal itself in the following year. Starting from crocoite the procedure was to powder the mineral and to precipitate the lead out through its reaction with hydrochloric acid (HCl in water). The residue was chromium oxide, CrO3. Heating this oxide in an oven in the presence of charcoal as a reducing agent gave the metal itself.
Vauquelin also analysed an emerald from Peru and discovered that its green colour is because of the presence of the new element, chromium. In fact, the name chromium is from the Greek word "chroma" meaning "colour", so named because of the many different coloured compounds displayed by chromium.
A year or two after Vauquelin's discovery, a German chemist named Tassaert working in Paris found chromium in an ore now called chromite. This ore, Fe(CrO2)2, is now an important source of chromium.