Mercury(II) sulfide, also known as cinnabar, mercuric sulfide, and mercury sulfide, is a chemical compound. Its chemical formula is HgS. It has mercury and sulfide ions in it. The mercury is in its +2 oxidation state.
Mercury(II) sulfide is a red or black solid. It is found in two forms; cinnabar (alpha form) and metacinnabar (beta form). The alpha form is more common. The beta form is made when a mercury(II) salt like mercury(II) chloride reacts with hydrogen sulfide. It reacts with only the strongest acids to make hydrogen sulfide and a mercury(II) salt again. It does not dissolve in water. It breaks down to sulfur dioxide and mercury metal when heated.
Mercury(II) sulfide is what makes the pigment vermilion. It has been used as a pigment and as a mercury ore. It was used to make lacquerware, containers covered with lacquer. It is also used in traditional Chinese medicine.