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.