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Formula: Bi2Cu3(PO4)2O2(OH)2.2H2O
Hydrated phosphate containing hydroxyl, bismuth-bearing mineral
Crystal System: Monoclinic
Specific gravity: 4.90 measured, 5.00 calculated
Hardness: 2 to 3
Streak: Light blue
Colour: Cerulean blue
Environments
Metamorphic environments
Hydrothermal environments
Mrázekite forms in vesuvianite-grossular
skarn invaded by secondary
copper, bismuth and
vanadium mineralisation
(Webmin) It is a rare secondary mineral formed by oxidation of polymetallic
sulphides. Associated minerals include chalcopyrite,
tetrahedrite, chalcocite,
malachite, pyromorphite,
pseudomalachite, libethenite,
reichenbachite, beudantite,
bismutite, mixite and
chrysocolla
(HOM).
Localities
The Wombat Hole prospect, Morass Creek gorge, Dartmouth, Towong Shire, Victoria, Australia, is a small
copper–bismuth–(tellurium)
exoskarn. Its main primary sulphide constituent is
bornite in a
grossular‒vesuvianite matrix.
Though the primary
bornite mineralisation has been nearly obliterated by weathering, there are
small relict patches containing exsolved grains of wittichenite and
chalcopyrite, as well as inclusions of
bismuth tellurides in the
tetradymite group, namely
sulphotsumoite and hedleyite.
Joséite-A and minute grains of native
bismuth have also been detected. Pervasive veining by
chrysocolla throughout the
garnet‒vesuvianite host contains
a range of unusual secondary
bismuth minerals, including mrázekite,
namibite, pucherite,
schumacherite and eulytine.
Other secondary minerals present include
wulfenite, bismutite,
azurite and malachite
(MM 86.4.606–618).
At Gademheim and Reichenbach, Odenwald, Bergstraße, Darmstadt, Hesse, Germany, mrázekite occurs in silicified
baryte veins; small isolated grains of ore minerals
(galena, chalcopyrite,
tetrahedrite, tennantite,
emplectite and wittichenite)
occur inside the vein material. Weathering of these primary
minerals leads to a great number of secondary minerals,
predominantly phosphates, arsenates and
vanadates of copper,
lead and bismuth.
A few milligrams of
blue mrázekite crystals were found at Gadernheim associated with
chalcopyrite, chalcocite,
malachite, goethite,
pyromorphite and beudantite.
At Reichenbach, mrazekite is associated with bismutite,
preisingerite, mixite and
reichenbachite.
Mrázekite forms crusts and spherical aggregates; idiomorphic crystals, less than 0.5 mm in size, with
well-developed faces, are rare
(CM 32.365-372).
At the type locality, the Podlipa deposit, Ľubietová, Banská Bystrica District, Banská Bystrica Region, Slovakia,
mrázekite forms
as a secondary mineral derived by oxidation of mainly
chalcopyrite and
tetrahedrite (AM 77.1306)
in the oxidation zone of an ore deposit containing chalcopyrite,
tetrahedrite,
pseudomalachite,
apatite and an unknown primary
bismuth mineral.
The mrázekite occurs as slender needles isolated or loosely grouped as small rosettes in a
quartz matrix (Mindat). Associated minerals include
quartz, libethenite,
pseudomalachite and
euchroite
(Dana).
Tetrahedrite and an unidentified sulphosalt of
bismuth are considered to have provided
copper, bismuth and
arsenic for the formation of mrdzekite; the phosphorus originated
from the breakdown of pseudomalachite or
apatite from the host rocks
(CM 30.215-224).
At La Borracha mine, Aldeanueva de San Bartolomé, Toledo, Castile-La Mancha, Spain, mrázekite is found with
pseudomalachite
(Mindat photo).
Mrázekite from La Borracha - Image
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