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Formula: Ca2Cu9(AsO4)4(CO3)(OH)8.11H2O
Hydrated arsenate containing hydroxyl
Crystal System: Monoclinic
Specific gravity: 3 to 3.2 measured
Hardness: 1½ to 2
Streak: Paler than unpowdered colour
Colour: Turquoise-blue, blue-green; light bluish green in transmitted light.
Solubility: Soluble in acids and ammonia
Common impurities: S,O
Environments:
Tyrolite is an uncommon secondary mineral in the
oxidised zone of copper deposits, typically formed
by alteration of tennantite(HOM) and associated with
tennantite, erythrite,
malachite, azurite,
brochantite, chrysocolla,
aurichalcite, cuprite and
iron oxyhydroxides
(Dana, HOM).
Localities
The type locality is Falkenstein, Falkenstein mining district, Schwaz District, Tyrol, Austria.
Tyrolite from Falkenstein - Image
In the Tintic Mineral District, Utah, USA, some very fine specimens of tyrolite have been found. It is
relatively common in the deposits where arsenate minerals are abundant.
Specimens of quartz with goethite
from several centimetres to tens of centimetres and with pale blue-green tyrolite sprays on fracture surfaces
and in vein fillings are among the largest and finest Tintic examples of tyrolite. The best crystals occur in
a matrix of quartz where enargite
has been partially or wholly altered near voids where nice single crystals and crystal clusters are able to form.
Single tyrolite crystals reach 1 cm only exceptionally. When tyrolite crystals embedded in
quartz are first exposed by breaking the
quartz, the tyrolite looks bright blue and glassy, but after a period
of being exposed to the atmosphere the crystals very commonly dehydrate, becoming a much paler, less lustrous,
opaque blue
(MinRec 55.2.226).
The tyrolite is associated with
chalcophyllite
and conichalcite
(Dana).
Tyrolite from Tintic - Image
At the Gold Hill Mine, Gold Hill, Gold Hill Mining District, Tooele County, Utah, USA,
juanitaite occurs on the 46-meter level, as fine-grained coatings on cavity
walls in quartz veins, associated with
connellite, tyrolite and
azurite
(CM 40.254).
Tyrolite from Gold Hill - Image
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