Definition
Essexite which is also known as nepheline monzogabbro, is a dark gray or black holocrystalline plutonic Iigneous Rock
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
History
Origin
USA
Italy
Discoverer
Unknown
Unknown
Etymology
From the locality in Essex County, Massachusetts,US
From a Latin word tophous then in Italian tufo and finally tuff
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock