This is the first time that indium mineralisation has been systematically documented in SW England.

Indium in SW England is primarily associated with Early-Permian peraluminous granite magmatism.

Cadmium and Ga were abundantly available prior to the emplacement of the granites.

In deposited primarily in the sulphide portions of granite-related skarn and vein systems.

The highest In concentrations are associated with the Carnmenellis and St Agnes pluton, and in this respect follows Sn.

Indium is hosted by chalcopyrite and sphalerite with less in cassiterite, stannite group minerals and tennantite.

The majority of the indium budget is in chalcopyrite.

Roquesite and other discrete In minerals formed where In-bearing chalcopyrite and sphalerite have been replaced.

No In was detected in löllingite, arsenopyrite, galena, bornite, chalcocite and pyrrhotite.

No In was detected in rutile, haematite, magnetite, tourmaline, biotite, and chlorite.

Scattered In in pyrite relate to impurities rather than solid solution.

The In deportment varies between parageneses with different sphalerite morphologies.

The mechanism of In incorporation into sphalerite varies with different morphologies.

Remobilisation of In from granite-related parageneses led to localised concentration into Triassic crosscourse veins.