Gianellaite

gianellaite

terlinguaite

montroydite

cinnabar

Images

Formula: (Hg₂N)₂(SO₄)(H₂O)_x
Anhydrous sulphate, mercury-bearing mineral
Crystal System: Isometric
Specific gravity: 7.19 measured, 7.13 calculated
Hardness: 3
Streak: Light yellow
Colour: Straw-yellow
Solubility: Not attacked at 20 to 100^oC by sulphuric acid (l:l), concenrated nitric acid, or hydrofluoric acid (HF). Decomposed by concentrated hydrochloric acid at room temperature (Mindat)
Environments

Hydrothermal environments

Localities

At the Clear Creek claim, Goat Mountain, San Benito county, California, USA, gianellaite has been found in a mercury deposit in silicate–carbonate rock hydrothermally altered from serpentinite (HOM).

At the type locality, Mariposa mine, Brewster county, Texas, USA, gianellaite occurs as a secondary mineral coating fracture surfaces in oxidised portions of a hydrothermal mercury deposit, the nitrogen likely derived from decaying organic matter (Webmin). The gianellaite occurs as rosettes of flattened subhedral crystals, rarely as euhedral crystals 0.2 to 1.0 mm in diameter of distorted octahedra. Associated minerals include terlinguaite, calomel, montroydite, native mercury, cinnabar, hematite and calcite; gianellaite is a late-formed mineral (AM 62.1057, HOM).

Back to Minerals