I was reading Trounson and there seemed to be non-agreement as to whether the Perran Iron lode was underlain by a truly magnificent copper deposit.
I wonder whether this was drilled, or whether new information came to light about the geology of that district. I gather mid way along Perranporth Beach, there is a degree of "spotting" of the killas, indicating the close proximity of the granite, I assume that it's quite possible that it drops into a copper/etc lode.
Interesting stuff those Trounson books.