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
Pumice is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals
From Old French pomis, from a Latin dialect variant of pumex
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock