In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Frongoch like this:
LISBURNE, a place of lead-mines in the NE of Cardigan; near Hafod-Park, 14 miles ESE of Aberystwith. The mines belong to the Earl of Lisburne, employ a large number of persons, and produce about 3,000 tons of lead a year. The main veins of ore run from E to W, and are from 4 to 6 feet thick; and the lesser veins thin out from the main ones, and can be traced at rocky spots of the hill, and at the sides and in the beds of neighbouring brooks.
A variety of sources say that Frongoch was the main centre of the Lisburn Mines, and that the Lisburne Mines chapel was nearby. More evidence would be helpful. Additional information about this locality is available for Llanafan
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Frongoch has changed, please see our redistricted information for the modern district of Ceredigion. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Frongoch and units named after it.
GB Historical GIS / University of Portsmouth, History of Frongoch, in Ceredigion and Cardiganshire | Map and description, A Vision of Britain through Time.
Date accessed: 05th December 2013
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Frongoch".