Worked E-W Pilkington and Cathole Vein. Several filled shafts and mounds.

easternmost workings of the mine are located on Gwernymynydd Farm. Several remnants of mining activity can still be identified in the landscape. A shaft and horse whim platform, likely No. 1 Shaft or St. Catherine’s Whimsey, is situated in a field east of the road to Fronissa at SJ 2220 6250. Nearby, at SJ 2230 6255, a filled shaft approximately 4 meters in diameter can be found, though there is no evidence of a whim. Additional filled shafts of varying sizes exist at SJ 2240 6255, SJ 2245 6260, SJ 2250 6260, and SJ 2250 6255. Some of these sites contain ironstone nodules and brittle dark shales, which suggest a coal-related geological composition.

A mound at SJ 2270 6260 appears to be a waste dump rather than a former shaft. The presence of coal-related geological features throughout the site indicates that some of these workings were likely exploratory or coal trial operations.

Mining in the area dates back to the 18th century when the Lords of Mold operated St. Catherine’s Mine, which later became known as the Gwernymynydd Mine. The Pilkington and Cathole Veins extend eastward from the River Alyn, and the mine sett was located to the east of the Cathole sett. In the 19th century, the Glan Alyn Mining Company took over operations, continuing to extract valuable minerals from the site.

One of the notable historical features is an arched stone adit level, constructed in 1739. This structure still exists today, situated just below the modern By-Pass road near Bryn Coch Farm at grid reference SJ 2270 6262.

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