Some of the unusual types of granite in the St Austell mass are distinguished by having an exceptionally high lithium content, mainly contained in a pale brown mica called zinnwaldite.  Lithium is the lightest metal known and has important applications in aerospace and batteries (many familiar modern electronic items, such as calculators, laptops and mobile phones are powered by lithium batteries). Because of its very low content of dark iron bearing minerals, this granite is a superb parent for china clay and also can be used as a kind of 'china stone' (see Boulder No. 2 for an explanation of what china stone is). 

Granite containing a high content of lithium mica occurs in two main areas: around Nanpean and Treviscoe and about 1 kilometre north of here in the Hensbarrow mass (Gunheath china clay pit).  This specimen has a feint mauve colour; small quantities of the mauve coloured mica called lepidolite, which has a high lithium content, occur in this rock. If fusion nuclear power ever becomes a reality, or if we drive lithium-powered battery driven cars in the future, then huge quantities of lithium will be required.  The St Austell granite is the largest lithium resource in the EU.  This granite also makes a good building stone and St Paul's Church at Charlestown is partially built from stone quarried about 1 kilometre from here.