1 Definition
1.1 Definition
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
Pumice is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From French, Latin lignum wood + -ite1
From Old French pomis, from a Latin dialect variant of pumex
1.4 Class
Sedimentary Rocks
Igneous Rocks
1.4.1 Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
1.5 Family
1.5.1 Group
1.6 Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock