Drove past this on the minor road between Tal-y-bont (which is on the A487 between Machynlleth and Aberystwyth) and the Nant y Moch reservoir, in the general Plynlimon area.

Brief Internet search failed to provide a definite answer, does anyone recognise it?

There were many other ex-mining sites dotted along the road, might be worth a day's mooching!

Phil