Area: 2.55 hectares.

Description and Reasons for Notification: 

The megacrystic granite of St. Michael’s Mount is a fractured granite cusp of the Cornubian batholith. The granite contains disseminated tin mineralisation and has been invaded by a swarm of sub-parallel, greisen-bordered, mineral veins which are excellently exposed over a wide area on the wave-cut platform. 

The extent of the exposure permits the opportunity to study variation in the mineralogy and chemistry of the veins both laterally and along the strike, as well as the nature of the alteration produced by the greisenization. The interest compliments that observed at Cligga Head but can be observed in plan on St. Michael’s Mount rather than in vertical exposure.