Images
Formula: Cu3Te6+O6
Anhydrous tellurate
Crystal System: Isometric
Specific gravity: 6.65 calculated
Hardness: 3
Streak: Light green
Colour: Green
Luminescence: Not fluorescent under long wave or short wave UV
Common impurities: Pb,Ni,Si
Environments
Sedimentary environments
Hydrothermal environments
Mcalpineite is a very rare secondary mineral, formed
by alteration of tellurides and
tellurium-bearing sulphides
(HOM).
Localities
At the Gambatesa Mine, Reppia, Ne, Genoa, Liguria, Italy, mcalpineite occurs in a
quartz vein mainly as yellowish green earthy crusts consisting of poorly
crystallised mcalpineite intergrown with an unidentified copper -
tellurium phase, as well as quite pure aggregates of euhedral
emerald-green crystals (individually reaching up to 50 µm), associated with black fragments of
paratellurite and weissite
(AM 98.1899-1905).
Mcalpineite from the Gambatesa Mine -
Image
At the type locality, the McAlpine Mine, Peñon Blanco Peak, Coulterville Mining District, Tuolumne County,
California, USA, mcalpineite is an extremely rare constituent at the long-abandoned mine. Only four
mcalpineite-bearing specimens have been identified to date (1994) from this locality. The mcalpineite
is found as isolated 0.5 mm-sized emerald-green cryptocrystalline crusts on white, well crystallised
quartz, associated with fuchsite
(locally known as mariposite). Metallic phases include pyrite,
acanthite, hessite,
electrum, altaite,
native silver, galena,
pyrargyrite, sphalerite and
owyheeite. Secondary
nonmetallic minerals include chlorargyrite,
choloalite, keystoneite,
mimetite, azurite,
malachite, annabergite,
calcite, goethite and
hematite.
The mcalpineite occurs as isolated 0.5 mm-sized emerald-green crusts on white
quartz
(MM 58.417-424).
At the Centennial Eureka Mine, Eureka, Tintic Mining District, Juab County, Utah, USA, underground mining was
probably discontinued at least sixty years ago, and the workings are now essentially inaccessible. The ore bodies
are contained for the most part in Cambrian (538.8 to 485.4 million years ago)
dolostone and in Ordovician (485.4 to 443.8 million years ago)
limestone.
Primary mineralisation consists mainly of
enargite with lesser pyrite,
chalcopyrite and galena,
hosted in a gangue of quartz,
bladed baryte and cave-deposit
calcite.
Prior to 1994 a small mining operation bulldozed the large dumps of the mine for re-processing, and exposed boulders
of mineralised rock. These boulders are characterised by corroded enargite
and diverse secondary hydrated
arsenate assemblages, all in a
gangue of quartz and
baryte. On several of these boulders, mcalpineite occurs as
interstitial olive-green coatings and as millimetre-sized dark green-black cryptocrystalline nodules lining drusy
quartz vugs. Directly associated minerals include green spherules of
xocomecatlite,
eurekadumpite, utahite,
hinsdalite-svanbergite
crystals and minor goethite
(MM 58.417-424, MinRec 55.2.213).
Mcalpineite from the Centennial Eureka Mine -
Image
Back to Minerals