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Formula: Fe2TeO6
Tellurate
Crystal system: Tetragonal
Specific gravity: 5.91 calculated
Streak: Yellow-brown
Colour: Greyish yellow, olive-green, brownish black
Luminescence: Not fluorescent under short wave or long wave UV
Environments
Sedimentary environments
Hydrothermal environments
Andymcdonaldite is a relatively new mineral, approved in 2019.
Localities
At the type locality, the Wildcat Project, Detroit Mining District, Juab County, Utah, USA, andymcdonaldite
occurs as thin fracture coatings on gold-,
tellurium- and bismuth- rich
jasperoid, and as partial matrix-fillings of
brecciated jasperoid.
One area of jasperoid boulders contains exceptionally high
concentrations of metals (gold 301 ppm,
tellurium 3800
ppm, bismuth 1935 ppm) and this is where
tellurium oxysalt mineralisation has been found.
Andymcdonaldite occurs sparingly as thin yellowish-brown to brownish-black coatings on freshly broken rock
fractures. Associated minerals include abundant white to colourless or pale tan
carlfriesite, crystals of
tlapallite, beudantite,
beyerite, brochantite,
clinobisvanite, eckhardite,
frankhawthorneite, gold,
hedyphane, khinite,
malachite, mcalpineite,
paratellurite, tellurite,
tellurium and xocolatlite.
Fischesserite, iodargyrite,
naumannite and petrovskaite
are probably also present.
The andymcdonaldite, carlfriesite, and other oxysalt minerals at
Wildcat likely formed from oxidation of primary
tellurium and/or telluride phases,
during late-stage, weathering-related oxidation. Remnant tellurium in rare
partially oxidised jasperoid is closely associated with
paratellurite and tellurite.
Intermediate oxidation zones are dominated by carlfriesite with minor
tlapallite. Closer to the original surfaces of
jasperoid boulders,
carlfriesite is absent but andymcdonaldite and
xocolatlite are present. In places, andymcdonaldite encrusts
carlfriesite. On the original exposed surfaces of
jasperoid boulders, andymcdonaldite and
xocolatlite are largely missing but black-coloured
manganese-bearing oxides are present
(CM 58.1.85-97).
Andymcdonaldite from the Wildcat Project -
Image
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