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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 the village of Luxulyan in Cornwall, England, where this variety of granite is found
Coarse Grained Rock, Opaque Rock
Ignimbrite is a volcanic rock consisting mainly of pumice fragments, formed by the consolidation of material deposited by pyroclastic flows
From Latin ignis fire + imber, imbr- shower of rain, storm cloud + -ite
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock