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Formula: [Pb8O2Zn(OH)6](SO4)4.6H2O
Thiosulphate (containing [S2O3]2- groups)
Crystal System: Monoclinic
Specific gravity: 5.173 calculated for the empirical formula and 5.177 for the ideal formula
Hardness: 2
Streak: White
Colour: Colourless
Luminescence: No flurescsnce under long wave or short wave UV
Solubility: In room-temperature dilute hydrochloric acid, sulfatoredmondite immediately becomes opaque and
then slowly dissolves
Environments
Metamorphic environments
Hydrothermal environments
Sulfatoredmondite is a new mineral, approved in 2021 and to date (January 2024) 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
Sulfatoredmondite crystals occur as colourless, transparent stout prisms with wedge-shaped terminations
up to about 2 mm in maximum dimension
(CJMP 61.189-202).
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