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Formula: Cu6Al(AsO4)3(OH)6.3H2O
Hydrated arsenate containing hydroxyl,
mixite group
Crystal System: Hexagonal
Specific gravity: 3.50 measured, 3.49 calculated
Hardness: 3 to 4
Streak: Greenish white
Colour: Blue-green, yellow-green
Solubility: Dissolves slowly in dilute hydrochloric acid
Environments
Goudeyite is a rare secondary arsenate.
Localities
At the Mangabeira deposit, Monte Alegre de Goiás, Goiás, Brazil, the
tin–indium mineralised area comprises
lithium-rich siderophyllite
granite,
topaz–albite
granite, quartz –
lithium-mica
greisens and a vein of
indium-rich
quartz–topaz rock, mainly composed of
quartz, topaz,
zinnwaldite, arsenopyrite
and cassiterite. Accessory minerals include
sphalerite, ferberite,
löllingite, chalcopyrite,
bismuthinite, galena,
stannite-group minerals,
tennantite, argentite and
roquesite. Secondary
minerals include bornite, digenite,
covellite, scorodite,
phenakite, native copper,
yanomamite, dzhalindite,
metazeunerite,
pharmacosiderite,
segnitite, chenevixite and
goudeyite
(CM 43.1393–1400).
At Chessy, France, goudeyite is associated with malachite and
montmorillonite
(HOM).
At the type locality, Majuba Hill Mine, Antelope Mining District, Pershing county, Nevada, USA, goudeyite is a
rare secondary mineral in a hydrothermal
copper-tin orebody in
rhyolite porphyry and
breccia
(HOM).
Primary ore minerals include
chalcopyrite, arsenopyrite,
pyrrhotite, pyrite and
cassiterite. Oxidation occurred along fault zones, and
secondary minerals were deposited in fractures.
Goudeyite, and also parnauite, generally occurs alone on
limonite-stained fracture
surfaces. Goudeyite came from a small stope near the entrance to the Copper Stope.
Secondary minerals commonly occurring nearby include
olivenite,
clinoclase, cornwallite,
strashimirite, scorodite,
pharmacosiderite, arthurite,
metazeunerite, chalcanthite and
chrysocolla. Less commonly occurring nearby minerals include
spangolite,
chalcophyllite, malachite,
azurite and brochantite
(AM 63.704-708).
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