Sulphide, sphalerite group, gallium-, indium- and zinc- bearing mineral
Colour: Dark grey
Luminescence: Non-fluorescent under UV
Plutonic igneous environments
Although ishiharaite was approved in 2013, to date (June 2022) it has been reported only from the type
The Type Locality, the Nueva Esperanza vein, Capillitas mining district, Andalgalá Department, Catamarca Province, Argentina, is an epithermal precious- and base- metal vein deposit, that has been mined for gold since pre-Colombian times. Since the second part of the last century, mining has been restricted to the extraction of pink banded rhodochrosite, the main gangue mineral in some of the veins, and for which the Capillitas mine is internationally known.
The precious- and base- metal vein mineralisation has more than 100 primary and secondary species described in the literature. The mine is the type locality for two other minerals, catamarcaite and putzite.
Ishiharaite was found in one sample from the Nueva Esperanza vein, that is hosted in granite. The sample is mainly composed of sphalerite, pyrite, tennantite, chalcopyrite, enargite, galena, gold, stannoidite, stannite and hübnerite, with chalcocite and covellite as secondary minerals in a quartz gangue.
The primary mineral ishiharaite occurs as subhedral, equidimensional, individual grains, 20 to 50 μm in size, included in tennantite and associated with sphalerite, pyrite, chalcopyrite and galena. One of the grains has very small (<1 μm) inclusions of chalcopyrite, while the other is surrounded by a discontinuous rim of that mineral. Ishiharaite formed at ∼245oC during a relatively late stage of mineralisation. Possibly it was formed during decreasing temperatures by exsolution of the indium and gallium contents carried in tennantite.
The paragenetic sequence of the Nueva Esperanza vein is quartz → pyrite → enargite → tennantite → sphalerite → chalcopyrite → ishiharaite → galena → gold → stannoidite → stannite → hübnerite → chalcocite → covellite
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