Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock
Luxullianite is a rare type of granite, known for presence of clusters of radially arranged acicular tourmaline crystals which are enclosed by phenocrysts of orthoclase and quartz in a matrix of quartz, tourmaline, alkali feldspar, brown mica.
From German which means hornstone
From the village of Luxulyan in Cornwall, England, where this variety of granite is found
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock