gordaite

{{infobox mineral | name = Gordaite | image = Gordaite.jpg | alt = | caption = Pale blue gordaite associated with deep green crystals of herbertsmithite from the San Francisco Mine, Caracoles, Antofagasta Region, Chile. | category = Sulfate mineral | formula = NaZn4(SO4)(OH)6Cl·6H2O | IMAsymbol = Gda | molweight = | strunz = 7.DF.50 | dana = | system = Trigonal | class = Rhombohedral () (same H-M symbol) | symmetry = P | unit cell = a = 8.413, c = 13.095 [Å]; Z = 2 | color = Colorless to white, pale green with copper substitution | colour = | habit = Thin tabular flakes or blades, in rosette aggregates | twinning = | cleavage = Perfect on {0001} | fracture = | tenacity = Flexible | mohs = 2.5 | luster = Vitreous to pearly | streak = | diaphaneity = | gravity = 2.627 | density = | polish = | opticalprop = Uniaxial (-) | refractive = nω = 1.561 nε = 1.538 | birefringence = δ = 0.023 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = }} Gordaite is a sulfate mineral composed primarily of hydrous zinc sodium sulfate chloride hydroxide with formula: NaZn4(SO4)(OH)6Cl·6H2O. It was named for the discovery location in the Sierra Gorda district of Chile. Gordaite forms as tabular trigonal crystals.

Gordaite first appeared after a research dive in September 1984 from the Juan de Fuca Ridge of the northeastern side of the Pacific Ocean. Gordaite was also described from weathered slag deposits as a result of copper smelting in Hettstedt, Germany. The mineral exhibits a hexagonal shape with clear or white (green if cuprian – Cu2+) crystals ranging from planar to broad habit and has a point group of . Gordaite commonly occurs near minerals such as sphalerite, boleite and gypsum. The most recent finding occurred in the San Francisco mine in Chile where copper-zinc sulfide deposits were found.