Definition
Origin
Discoverer
Etymology
Class
Sub-Class
Group
Other Categories
Gritstone or grit is a hard, coarse-grained, siliceous sandstone
Coarse Grained Rock, Opaque Rock
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
From a Latin word tophous then in Italian tufo and finally tuff
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock