Mount Gabriel, County Cork, Ireland

The Devonian Castlehaven Formation carries minor green siltstone and calcrete conglomerate horizons and has suffered low grade greenschist metamorphism. Finely disseminated copper and copper-iron sulphides occur within these horizons but also are concentrated along fine-scale, post-metamorphic fabrics. These ores were mined during the Bronze Age in one of Europe's oldest metalliferous mines.

Major Minerals:

Digenite, bornite, chalcocite, djurleite, blaubleibender covelline, malachite

Minor Minerals:

TiO2 minerals, covelline, cuprite, carbonaceous matter

Trace Minerals:

Include pyrite, chalcopyrite, haematite, acanthite, native copper


Detrital TiO2 mineral grains have euhedral TiO2 mineral overgrowths. Detrital haematite is absent and secondary haematite is rare. Copper sulphides form cements around euhedral silicates or lie along the cleavage of chlorite-muscovite. Coarser grained copper sulphides lie along cross-cutting veinlets and joint planes. Bornite is replaced by djurleite and chalcocite along (100) crystallographic planes. Digenite is replaced along its cleavage by covelline and blaubleibender covelline. Locally, chalcocite-djurleite carries discrete silver-rich inclusions that are photosensitive


Reilly, 1986; Ixer, 1987