Kōrero: Coal and coal mining

Rank of coal

The rank of coal is determined by how deeply the original plant matter was buried. Plant material buried close to the surface becomes peat, while plants buried very deeply become semi-anthracite coal. As the depth increases, the proportion of water in the coal is reduced, and the proportion of carbon increases. These changes also affect the volume of the coal. As it becomes higher in rank, water and gaseous hydrocarbons are driven off, and the coal becomes more compressed.

Te whakamahi i tēnei tūemi

Te Ara – The Encyclopedia of New Zealand

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Source: GNS Science

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Te tuhi tohutoro mō tēnei whārangi:

Alan Sherwood and Jock Phillips, 'Coal and coal mining - The nature of coal', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/table/7408/rank-of-coal (accessed 12 August 2020)

He kōrero nā Alan Sherwood and Jock Phillips, i tāngia i te 12 Jun 2006, updated 7 Sep 2016