Definition
Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth
Rhyolite is a fine-grained igneous rock which is rich in silica
History
Origin
Egypt
North America
Discoverer
Georgius Agricola
Ferdinand von Richthofen
Etymology
From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites
From German Rhyolit, from Greek rhuax lava stream + lithos stone
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock