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 decreases 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

Ngā whakaahua me ngā rauemi katoa o tēnei kōrero

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 15 June 2024)

He kōrero nā Alan Sherwood and Jock Phillips, i tāngia i te 12 Jun 2006, reviewed & revised 14 Apr 2021