Schuetteite

schuetteite

cinnabar

mercury

Images

Formula: Hg3O2(SO4)
Valence: Hg2+3O2(S6+O4)
Anhydrous sulphate of mercury
Crystal System: Trigonal
Specific gravity: 8.18 measured, 8.36 calculated
Hardness: 3
Colour: Canary-yellow, orange-yellow, brownish yellow. Does not darken on exposure to light, unlike the yellow mercury oxychlorides, such as terlinguaite
Environments

Hydrothermal environments
Furnace bricks

Schuetteite has been found as a supergene mineral in several mercury deposits in the more arid parts of the western United States, and is a common product on dumps of burnt ore and bricks from old mercury furnaces. In natural occurrences schuetteite has been found on cinnabar surfaces exposed to sunlight. It is believed to have formed through direct oxidation of cinnabar by oxygen-bearing surface water with sunlight providing energy to cause the reaction.
On dumps of burnt ore and on furnace bricks schuetteite forms beneath the surface and a different reaction is required. In these places it appears to result from the action of strongly acid sulphate waters on metallic mercury. This reaction requires higher acidity and more strongly oxidising conditions than are normally met in nature; in those natural environments where such conditions might occur, mercury generally is present as a sulphide rather than as the native element. It therefore seems unlikely that mercury deposits have anywhere developed the conditions that lead to the formation of schuetteite in this way. (AM 44.1026-1038).

Localities

At the type locality, the Oceanic Mine, Cambria, Cambria-Oceanic Mining District, Santa Lucia Mts, San Luis Obispo County, California, USA, schuetteite has been found as yellow thin films, as a recently formed secondary mineral in the mercury deposit, typically formed on cinnabar exposed to sunlight (Mindat).
Schuetteite from the Oceanic Mine - Image

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