Area: 1.8 hectares
Description and Reasons for Notification:
These quarries provide excellent exposures of two late-magmatic varieties of the varied St. Austell granite mass (of Permo-Carboniferous age). Fluorite granite predominates, but this is accompanied by irregular patches of non-megacrystic lithium-mica granite. The site is significant in illustrating that the contacts between the two rock-types are transitional and non-intrusive in nature and they may be accounted for by metasomatic over-printing of an original biotite granite by a lithium- rich fluid. The biotite was replaced by a lithium mica while elsewhere high fluorine contents resulted in the crystallisation of fluorite.