Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Marl is an unconsolidated sedimentary rock consisting of clay and lime
History
Origin
Egypt
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Discoverer
Unknown
William Smith
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From Old French marle, from Late Latin marglia
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
Plutonic
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Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock