Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
History
Origin
Egypt
-
Discoverer
Unknown
Unknown
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock