Identifying Mercury Minerals

Closed Tube Test. The powdered mineral is thoroughly mixed with dry sodium carbonate and placed in a closed tube and then heated. The sodium carbonate will decompose the mineral and liberate metallic mercury, which will volatilize and condense in the upper part of the tube.

Precipitation on Copper. Boil the powdered mineral with hydrochloric acid, into which some powdered pyrolusite, MnO2, has been placed. The chlorine evolve by the action of the acid on the manganese dioxide will serve to dissolve the mercury mineral. It into this solution a clean strip of copper is placed (accent which has been cleaned with a little nitric acid will serve), it will become covered by a thin coating of metallic mercury.

The chief and only common mineral of mercury is cinnabar, HgS