Silver sulfide


Silver sulfide is an inorganic compound with the formula. A dense black solid, it is the only sulfide of silver. It is useful as a photosensitizer in photography. It constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in most solvents, but is degraded by strong acids. Silver sulfide is a network solid made up of silver and sulfur where the bonds have low ionic character.

Miscellanea

Three forms are known: monoclinic acanthite, stable below 179 °C, body centered cubic so-called argentite, stable above 180 °C, and a high temperature face-centred cubic stable above 586 °C. The higher temperature forms are electrical conductors. It is found in nature as relatively low temperature mineral acanthite. Acanthite is an important ore of silver. The acanthite, monoclinic, form features two kinds of silver centers, one with two and the other with three near neighbour sulfur atoms. Argentite refers to a cubic form, which, due to instability in "normal" temperatures, is found in form of the pseudomorphosis of acanthite after argentite.