Luxullianite

Luxullianite is a rare type of porphyritic tournalinized granite, notable for the presence of clusters of radially-arranged acicular tourmaline crystals enclosed by phenocrysts of orthoclase and quartz in a matrix of quartz, tourmaline, alkali feldspar, brown mica, and cassiterite.
The name originates from the village of Luxulyan in Cornwall, United Kingdom, where this type of granite is found. An example may be seen in the Arthur [Wellesley, 1st Duke of Wellington|Duke of Wellington]'s tomb in St [Paul's Cathedral] in London. Some luxullianite is also used in the Porphyry Hall of the Place House in Fowey.