Definition
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
An iron rich extrusive rock found as a member of the alkali basalt magma series
History
Origin
USA
Isle of Mull, Scotland
Discoverer
Unknown
Ben More
Etymology
From pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
From the name of discoverer, Ben More
Class
Metamorphic 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