Overview

Mercury(II) sulfide (MER-kyuh-ree two SUL-fide) occurs in two forms, red and black. Red mercury(II) sulfide, commonly known as cinnabar, begins to change color when heated to temperatures of about 250°C (500°F) and converts to the black form at 386°C (727°F). If heated further, it sublimes (changes directly from a solid to a gas without first melting) at 583.5°C (1,082°F). If allowed to cool, it then reverts to its original reddish color. Black mercury(II) sulfide goes through a similar process, changing to its red counterpart before melting at 583.5°C (1,082°F). Some authoritative resources give significantly different temperatures for these transitions. Red mercury(II) sulfide occurs naturally as the mineral cinnabar, while black mercury(II) sulfide occurs only rarely in nature, then as the mineral metacinnabar (meaning "similar to cinnabar").

Key Facts

Other Names:

Mercuric sulfide; cinnabar; vermillion; Chinese red

Formula:

HgS...