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Formula: [Pb8O2Zn(OH)6](S2O3)4
Thiosulphate (containing [S2O3]2- groups)
Crystal System: Monoclinic
Specific gravity: 5.757 calculated for the empirical formula, 5.680 calculated for the ideal formula
Hardness: 2
Streak: White
Colour: Colourless to shades of brown
Luminescence: No fluorescence under long wave or short wave UV
Solubility: In room-temperature dilute hydrochloric acid, redmondite immediately becomes opaque and then
slowly dissolves.
Environments
Metamorphic environments
Hydrothermal environments
Redmondite is a new mineral, approved in 2021 and to date (June 2023) reported only from the type locality
Localities
At the type locality, the Redmond mine, Waterville Lake, Haywood county, North Carolina, USA, redmondite,
hydroredmondite and
sulfatoredmondite have been found underground. The ore, consisting
mainly of galena and sphalerite
with lesser amounts of chalcopyrite, occurs in an epithermal (low
temperature) vein system consisting of disconnected sulphide-bearing quartz
lenses near the contact between a granite
gneiss and a mica
schist. These redmondite minerals occur in a
secondary assemblage that comprises a variety of rare
lead-zinc-copper
sulphates, thiosulphates and carbonates, including bechererite,
chenite, elyite,
fassinaite, lahnsteinite,
lanarkite, lautenthalite,
namuwite, redgillite,
osakaite, sidpietersite,
steverustite and susannite, as
well as some more common secondary minerals such as
anglesite, brochantite,
caledonite, cerussite,
langite, leadhillite,
linarite, malachite,
posnjakite, schulenbergite
and wroewolfeite. Redmondite,
hydroredmondite and
sulfatoredmondite occur together in vugs in massive
galena-sphalerite-chalcopyrite-quartz,
in close association with anglesite,
cerussite, chenite,
elyite, gypsum,
lanarkite, steverustite,
susannite, and several other potentially new minerals.
The secondary mineral assemblage here is distinguished from any
analogous lead-zinc vein known, based on
the astonishing diversity of new and/or rare sulphate and thiosulphate minerals found within it. The formation of these
rare minerals appears to have been limited to small vugs within the galena-rich
ore where exotic metal coordination complexes were stabilised in stagnant solutions under
supergene conditions. It appears that at least some thiosulfate
precipitation occurred at near-neutral pH conditions in the weathered ore lenses
Redmondite crystals occur as colourless, transparent, equant rhombs up to about 1 mm in size
(The Canadian Journal of Mineralogy and Petrology 61.189-202).
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