Definition
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks
Travertine is a mineral consisting of layered calcium carbonate formed by deposition from spring waters
History
Origin
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Italy
Discoverer
Unknown
Marcus Vitruvius Pollio
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From Italian travertino a kind of building stone, from Tiburs, adjective from Tibur (Tivoli), in Italy
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
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Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock