Coal mining is the mining of coal. Colliery refers to the mine, and the associated buildings and machinery.

How coal is extracted from coal seams depends on how deep the seams are, and also the geology and geography of the area it's being mined in.

If the coal seams are near the surface, the coal is extracted by either:

• open pit mining, in some countries, synonymous with a quarry
• strip mining, coal is extracted by large machines in strips; the strata on top of the coal are allowed to fall back to where the seam was, once the mining has finished.

Most open cast mines extract lignite.

However most coal seams are too deep underground for open cast mining. Most coal is extracted by either:

• deep mining , The shaft is dug vertically deep into the ground. These tend to be the most productive pits and often contain high quality coals.
• drift mining , The shaft is dug into the side of a mountain. Drift mines are smaller than deep mines and are common in South Wales.

Mining can be very dangerous and although in the West disasters are now rare, pit collapses, explosions and flooding are still common in parts of the world. China tries to keep its mining disasters hidden, but news leaks out.

The industry has been subject to sometimes violent labor relations in the U.S. (for example, see Ludlow Massacre); union organizers were sometimes murdered by management.

Now coal mining is highly unionized, and the unions are sometimes militant. Mining communities are often close-knit and very religious with a strong sense of community spirit. They also tend to be strongholds of left-wing political parties.

See also

• Black lung disease
• Wilkes-Barre, Pennsylvania
• Harlan County, USA
• Acid mine drainage
• Coal Measures
• Mine fire
• Bootleg mining
• Mining Accidents