Definition
Gritstone or grit is a hard, coarse-grained, siliceous sandstone
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
History
Origin
Pennines, England
Italy
Discoverer
J.J. Ferber
Unknown
Etymology
From Grit + Stone
From a Latin word tophous then in Italian tufo and finally tuff
Class
Sedimentary Rocks
Igneous 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, Opaque Rock