It is typically produced synthetically but can also be found in nature as the extremely rare mineral coccinite.

[3] The various forms can exist in a diverse range of crystal structures and as a result mercury(II) iodide possesses a surprisingly complex phase diagram.

[4] Mercury(II) iodide is used for preparation of Nessler's reagent, used for detection of presence of ammonia.

Mercury(II) iodide is a semiconductor material, used in some x-ray and gamma ray detection and imaging devices operating at room temperatures.

[5] In veterinary medicine, mercury(II) iodide is used in blister ointments in exostoses, bursal enlargement, etc.