Greenockite and associated sulphide mineralization from the Caledonia mine, Blanca Creek, La Huerta Range, San Juan Province, Argentina

MOGESSIE, A.,; GALLIEN, F.; BERNHARD, F.; BAUER, C.; CASTRO DE MACHUCA, B.; MEISSL, E; BJERG, E. A.; DELPINO, S.

CANADIAN MINERALOGIST

Mineralogical Association of Canada

Año: 2009 vol. 47 p. 129 - 141

0008-4476

Different textural occurrences of greenockite associated with several ore minerals in varyingparageneses: Pyrite + Sphalerite + Galena + Chalcopyrite ± Arsenopyrite ± Pyrrhotite ± Bornite ± Tennantite ± Tetrahedrite ± Covellite ± Chalcocite ± Aikinite ± Wittichenite ± Matildite ±Berryite ± Miharaite ± Geocronite ± Hematite ± Magnetite are documented from mineralizedsamples of the Caledonia Group mines, Marayes mining district, La Huerta Range, San Juanprovince, Argentina, based on reflected light and scanning electron microscopic investigations.The mineralization is hosted mainly in metacarbonate outcrops in contact with the granulitebasement and associated intermediate to mafic meta-intrusive rocks. The identified greenockiteare divided into textural and chemical types 1 to 3. Type 1 greenockite has a Zn-content of lessthan 1 mol% ZnS, but a varying Fe-content from 0.2 up to 4.5 mol% FeS. Type 2 is Zn-rich with 10-25 mol% ZnS component and < 0.1 to 3 mol% FeS component, and type 3 has a Zn-content of 5-7 mol% ZnS component and FeS < 0.1 mol%. It is suggested that the presence of complex Ag-Cu-Bi-Pb sulphides point to a late stage, low-temperature overprint of the primary sulphide parageneses, accompanied by the formation of hypogene greenockite, at least partly at the expense of sphalerite. The near end-member composition of greenockite and late-stage sphalerite also indicate a low temperature formation.