What is coal?
Coal is a rock that can burn, and it is made from carbon, water and minerals. It was formed millions of years ago when plants fell into peat swamps and were buried by heavy earth and rocks. Over a very long time, the weight of the rocks and heat in the ground turned the plants into coal.
How old is it?
Most of the world’s coal was formed 300–350 million years ago. New Zealand coals are much younger – they were made 30–70 million years ago.
Kinds of coal
There are different kinds of coal with varying properties that determine how it can be used. The kinds of plants that eventually turn into coal differ, as do the minerals in the coal. The most important factor is how deeply the original plant material is buried. It begins as peat and as it becomes more compressed it gradually changes into lignite, sub-bituminous coal, bituminous coal or even (if it is buried deeply enough) anthracite.
There are coalfields in Northland, Waikato, Taranaki, the South Island’s West Coast, Otago and Southland.
Europeans began mining coal in New Zealand in the 1840s. At first, men went underground and dug out the coal with picks and shovels.
In the early 1900s men used explosives and compressed-air machines in mines to cut coal from the seam. The coal was loaded into wagons and taken out of the mine. From the 1990s high-pressure water jets were used to cut the coal in some underground mines.
By the 2000s mining was usually opencast. Earth and rock covering the coal was scraped and blasted away. When the coal was gone, the land was generally restored.
Underground mining was dangerous. Rocks fell, men were knocked over by the wagons carrying coal, there were explosions, and miners were suffocated by poisonous gases.
An explosion at the Brunner mine in 1896 was New Zealand’s worst industrial accident, with 65 people killed by toxic gas.
In the 2000s mining was generally safer because of government regulations and inspections, and because opencast (rather than underground) mining methods were used.
Explosions at the Pike River mine in 2010, which resulted in the deaths of 29 men, exposed ongoing safety issues for miners.
The government set up Workplace New Zealand to be responsible for all workplace safety issues, with a designated High Hazards Unit covering industries such as mining and petroleum exploration.
Many of the early miners came from Britain, where there was a tradition of trade unionism to improve miners’ working conditions. Many New Zealand mining towns became centres of strong union activity. Some of the union leaders later became members of parliament.