Definition
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.
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
England
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Discoverer
Unknown
Alexandre Brongniart and René Just Haüy
Etymology
From the village of Luxulyan in Cornwall, England, where this variety of granite is found
From Greek trakhus rough’ or trakhutēs roughness
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock