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Formula: [Pb8Zn3Cu2+(OH)16](SO4)2(S2O3)2.2H2O
Hydrated sulphate/thiosulphate of lead,
zinc and copper
Crystal system: Monoclinic
Specific gravity: 5.034 calculated for the empirical formula, 5.054 for the ideal formula
Colour: Blue
Luminescence: No fluorescence under long wave or short wave UV
Solubility: Blueridgeite rapidly turns opaque white from the formation of PbCl2 and then slowly
dissolves in dilute hydrochloric acid at room temperature
Environments
Blueridgeite is a new mineral, approved in 2024 and to date (October 2025) reported only from the
type locality.
Localities
The type locality is the Redmond Mine, Waterville Lake, Haywood County, North Carolina, USA. Here submillimetric
blue polycrystalline spheres of blueridgeite have been found with some colourless blades of
siligiite. Despite the preponderance of both sulphate
(S6+O4)2- and thiosulphate
(S6+O3S2-)2- minerals at the Redmond Mine, and of substitution of
sulphate for thiosulphate and vice versa, blueridgeite is the only mineral at the mine to incorporate both as
essential structural components ordered into distinct sites. Its structure is otherwise quite similar to that of
cherokeeite and
cuprocherokeeite.
The Redmond mine was a lead-zinc mine
where the ore, consisting primarily of galena and
sphalerite with lesser
chalcopyrite, occurs in an epithermal vein system of discontinuous
sulphide-bearing quartz lenses near the contact between a
granite gneiss and a
mica schist. Blueridgeite
occurs in small voids in the sulphide veins in close association with
cuprocherokeeite, elyite,
sidpietersite,
steverustite, susannite and
a potentially new Pb-Cu sulphate. It has also been found in association with
anglesite, bechererite,
caledonite, chenite,
cherokeeite, hanahanite,
haywoodite,
hydroredmondite,
lanarkite, linarite,
redmondite, siligiite,
sulfatoredmondite and
zincochenite
(CJMP 63.397-409).
Blueridgeite from the Redmond Mine -
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