Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
History
Origin
North America
Indonesia
Discoverer
Ferdinand von Richthofen
Cornish Gossen
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Cornish gossen from gos, blood from Old Cornish guit
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
-
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock