Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
-
-
Discoverer
Unknown
Alexandre Brongniart and René Just Haüy
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
From Greek trakhus rough’ or trakhutēs roughness
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock