1 Definition
1.1 Definition
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From French, Latin lignum wood + -ite1
From Old French esclate, from esclat (French éclat)
1.4 Class
Sedimentary Rocks
Metamorphic Rocks
1.4.1 Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
1.5 Family
1.5.1 Group
Not Applicable
Not Applicable
1.6 Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock