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Formula: (Cu,Zn)16(Te4+O3)2(AsO4)3Cl(OH)18.7H2O
Tellurite, arsenic-bearing
mineral
Crystal System: Monoclinic
Specific gravity: 3.76 measured, 3.826 calculated
Hardness: 2½ to 3
Streak: Light turquoise-coloured
Colour: Bright and deep blue-green to turquoise-coloured
Environments
Localities
At the type locality, the Centennial Eureka Mine, Eureka, Tintic Mining District, Juab County, Utah, USA,
eurekadumpite occurs in the oxidation zone of quartz-sulphide ores
containing tellurides (mostly
hessite) in small cavities and in fractures in
quartz. Associated minerals include
mcalpineite, malachite,
zinc-bearing olivenite,
goethite and unspecified
manganese oxides
(HOM).
The eurekadumpite occurs as separate compact spherulites, more frequent hemispheres, and rosettes up to
1 mm in diameter
(Mindat).
Eurekadumpite from the Centennial Eureka Mine -
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Other mines in the Tintic Mining District, Juab County, Utah, USA.
Eurekadumpite is one of the most abundant of the oxidised tellurium
species in the district. As well as the Centennial Eureka mine, it has also been found at the North Star mine in
abundance, and in several specimens from the Gold Chain mine and the Trixie mine. It generally occurs as blue spheres
on a quartz matrix; at the North Star mine it has also been found in varying
shades of green. When the spheres are broken, they show the typical micaceous habit of the crystals, occurring as
plates generally less than 1 micron thick, 500 microns wide, and rosettes or spheres up to 1 mm. Associated
minerals vary depending on the locality, but eurekadumpite has been found associated with
azurite, cesbronite,
dagenaisite, dugganite,
enargite,
frankhawthorneite,
goldfieldite, jensenite,
leisingite, malachite,
mcalpineite, olivenite,
pyrite, quetzalcoatlite,
scorodite, tellurite,
utahite, xocomecatlite and
zemannite. A single specimen with dark velvety green spheres of
eurekadumpite was found in direct association with volborthite
(MinRec 55.2.201).
Eurekadumpite from the Gold Chain Mine -
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