Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Arkose is a sedimentary rock, specifically a type of sandstone containing at least 25% feldspar
History
Origin
Brazil
France
Discoverer
Unknown
Alexandre Brongniart
Etymology
from French néphéline, from Greek nephelē
From Auvergne region of France used by a French geologist Alexandre Brongniart in 1826 who applied this term to some feldspathic sandstones
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
Plutonic
-
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock