Industrial mining began after the Roman conquest of Wales with large-scale extraction of gold, copper, lead, zinc and silver.
After the Mines Act of 1842 banned women, girls and boys under 10 from underground working, the use of pit ponies increased dramatically. They were mostly stabled underground and only came to surface during the colliery's annual holiday.
19th-century privately-owned mines made huge profits for their owners. One of the landowners of South Wales, the third Marquess of Bute, became one of the richest men in the world at the time.
The largest number of men ever to work in the Welsh coal mines was 271,000 in 1920.
Child and adult miners frequently suffered injury and disease associated with working conditions in the pits. Industrial bronchitis and coal workers' pneumoconiosis, also known as 'black lung' disease, were common as a result of inhaling coal dust over an extended period.
Coal use is responsible for 44% of the world's total carbon dioxide emissions!