1 Definition
1.1 Definition
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From French, Latin lignum wood + -ite1
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
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