1 Definition
1.1 Definition
Ignimbrite is a volcanic rock consisting mainly of pumice fragments, formed by the consolidation of material deposited by pyroclastic flows
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From Latin ignis fire + imber, imbr- shower of rain, storm cloud + -ite
From French, Latin lignum wood + -ite1
1.4 Class
Igneous Rocks
Sedimentary Rocks
1.4.1 Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
1.5 Family
1.5.1 Group
1.6 Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock