What is formed in the second stage during the formation of coal?
Lignite
Lignite is the second stage in the formation of coal. It contains more than 60% carbon. It is brown in colour but harder. The coal formation process starts from plants which in the presence of heat and pressure converts to peat to lignite to bituminous and finally to anthracite.
Plants → Peat → Lignite → Bituminous → Anthracite