Records of the Gogerddan estate deriving from the industrial exploitation of minerals and quarry stone on the estate. The majority relate to the mines and quarries in north Cardiganshire, 1656-1924, covering mostly the area between Aberystwyth and Machynlleth but also including Grogwynion at Llanafan. The group also contains a substantial quantity of letters and papers arising from the development of the Plynlimon and Hafan Tramway 1875-1919; and a small number of leases, letters and accounts relating to mining and quarrying in Merioneth, 1699-1913, Montgomeryshire, 1864-1881, and Flintshire, 1740. The papers record almost every aspect of lead, silver and copper mining in Cardiganshire, describing the initial surveys, the processing and extraction of ore, the equipment required, the output of the mines, the impact on the Cardiganshire landscape, the shipping of ores to Swansea, the investment and commercial aspects, and relations between the Gogerddan estate and the mining companies. It is interesting to note the involvement of investors and prospectors from Flintshire, Derbyshire, Cornwall, Scotland and London. This section is also a rich source of personal names, both of the mining contractors and their work-force. For the names of the mines and further details, see the sections below.