Welsh coal
was used to produce coke - you have two coalfields in the South of the country roughly divided by the River Tawe, you have the South Wales coalfield (the'valleys', Merthyr, Ebbw Vale and so on, They produced soft, bituminous coal, 'steam coal' then the
South West Wales coalfield, the Neath valley, Loughor and Aman valleys (where I am) and the Gwendraeth valley and areas even further West, even the Pembrokeshire tourist traps of Saundersfoot and Tenby had a thriving coal industry, apparently the coal ranges right out under the sea all the way to Ireland. The South West Wales coalfield was high quality hard coal (dug out by even harder men
) although ironmaster David Thomas devised a method for smelting iron from anthracite which was also used in Pennsylvania.
There's a seam of coal deep under the mountain opposite me called the peacock vein, the coal from that looks like black glass, you don't get your hands dirty handling it and, if you use it 'neat' it burns so intensely it will burn out your firelace within a few hours.