Definition
Pumice is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals
Gritstone or grit is a hard, coarse-grained, siliceous sandstone
History
Origin
Spain
Pennines, England
Discoverer
Unknown
J.J. Ferber
Etymology
From Old French pomis, from a Latin dialect variant of pumex
From Grit + Stone
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
-
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock