New Zealand's Coal Deposits

New Zealand has 8 billion tonnes of proven coal resources. The largest coal fields are in the Waikato, the West Coast and Southland, with production also in Taranaki, Nelson and Otago.

Image of a core sample containing breccia beneath coal, Rotowaro coalfield. Image from Julian Thomson.

Image of a core sample containing breccia beneath coal, Rotowaro coalfield. Image from Julian Thomson.

Most of New Zealand's coal has its origins in extensive coastal swamps or shallow inland basins. New Zealand coals are mainly 25 to 70 million years old – relatively young compared to many overseas coal deposits. This is due to the highly active geology of New Zealand. Peat deposits have been buried relatively quickly to suitable depths for ‘coalification’, followed by uplift and erosion that makes them accessible for mining. Read more about coal formation.

Less than 10% of New Zealand’s available coal reserves are bituminous, while 22% are sub-bituminous and 70% lignite.

Image Julian Thompson

North Island: The recoverable North Island coals of the Waikato are sub-bituminous grade. Higher quality coal is too deeply buried below Taranaki and a wide area off the West Coast. Gases and liquids driven off from these deeper coals are the source of the oil and gas fields of the Taranaki basin. Oil exploration drilling wells often pass through thick layers of coal over 4 km below the surface.

South Island: The Buller and Greymouth coalfields were buried deeply before being uplifted, and are therefore of a good bituminous quality. The Ohai coalfield in central Southland has sub-bituminous coals, whilst there are about 7 billion tonnes of poorer quality lignite distributed across Southland and Otago – New Zealand’s largest potentially recoverable coal reserve.