The Bute Hermatite Iron Ore Works began in October 22 1852 by Edward Lloyd and the proprietor was later Fothergill Rowlands. With the closure of the Bute iron ore mine in 1880 and Mwyndy iron ore mine four years later, the coal industry became the main source of employment. 

A colliery at Ynysmaerdy was sunk by the Powell Dyffryn Co. in 1922 and completed in 1926 but was never a success. It employed 300 men in 1931 but due to major water problems, the operation was halted from 1934 to 1937. On Whit Monday in June 1941, disaster struck when an explosion on the surface killed four men, although the miners underground were unharmed. Those killed were John Gregor (agent), Noah Fletcher (winding engineman), David Thomas (switchboard attendant) and Ernest Evans (banksman). The colliery never re-opened.

Two other collieries opened in the area during the early part of the century at Coedely, Cwm and Llanharan. The Great Western Colliery Co. began sinking Cwm Colliery in 1909 with the first coal produced in 1914. The two shafts of Margaret and Mildred were 750 yards deep and by 1918 603 men were employed there.

Powell Duffryn Associated Collieries Ltd took it over in 1928 and it linked with the Maritime Colliery in Pontypridd by 1931. The pit eventually closed in 1986. The Welsh Navigation Steam Coal Company began the sinking of two shafts at Coedely in 1901. No 1 Pit was sunk to a depth of 701 yards and No 2 pit to 763 yards. It was also equipped with coke ovens and by 1918 1,450 men were employed. By 1935 there were 30 coke ovens in operation.

The 1920s brought a period of expansion in industry to the area and the Llantrisant and Llantwit Fardre Rural District Council was empowered to build more houses. Schemes were started in Beddau, Pontyclun and in Penygawsi to accommodate a growing population. The land at Penygawsi was sold to the council by Rev Samuel of Penuel Chapel, High Street. Within the next year families occupied all the new houses at Heol Pen y Parc and Park View.

Cwm Colliery

The sinking of Cwm Colliery in 1909 by the Great Western Colliery Company Limited marked the beginnings of Beddau's rapid development.

Although it was situated in a village outside of Llantrisant, many residents of the old town travelled daily upwards from Brynteg to work there.

The company had been incorporated to sink pits in the Pontypridd area to provide steam coals for the Great Western Railway. The wife of the company's Managing Director, Mrs C.H. James, had the privilege of cutting the first turf. Among the local dignitaries were Lady Margaret and Lady Mildred Bramwell of Tir Mab Ellis. Their names were to continue an association with the colliery because the two shafts sunk were better known as the Margaret and Mildred Pits.

Sinking operations were still continuing in 1913 when the pit employed 212 men. By 1934 it was in full production employing 100 men on the surface and 780 men underground. Powell Duffrun Steam Coal Company acquired the colliery in 1928 and worked them until the mines were nationalised in 1947.

Cwm Colliery developed throughout the inter war years and after World War II, both manpower and production increasing significantly. An underground railway linking the Maritime Colliery, Pontypridd with Cwm was completed in 1931. In 1957 a similar railway linked Cwm with Coedely Colliery. The merger of these two pits created the largest colliery in the South Wales Coalfield. Production and manpower reached a peak in 1960 as Cwm Colliery employed 1,470 men and produced 324,794 tons.

Cwm coke works opened in 1958. It was designed to centralise and maintain the production of South Wales foundry coke. The coal mined at Cwm was very suitable for foundry coke given its low sulphur content. Cwm Colliery was closed by the NCB in 1986 and the coke works ceased production in June 2002