Definition
Pegmatite rock is a holocrystalline, intrusive igneous rock which is composed of interlocking phaneritic crystals
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
History
Origin
-
Iceland
Discoverer
R. J. Hauy
Unknown
Etymology
From Greek pegma, pegmat which means- thing joined together + -ite
From German Tachylite, from tachy- + Greek lutos soluble, melting
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock