AFCAT I 12 Feb 2022 Shift 1 Paper

Lignite, often referred to as brown coal, is a soft brown combustible sedimentary rock that is formed from naturally compressed peat.
Anthracite A very hard type of coal that burns slowly without producing a lot of smoke or flames
Granite It is a stone, It is one of the oldest and most durable building products available.
Bituminus Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt.