Steep cliffside workings largely inacessible from the top. A set of steps carved into the cliff gives access from the sea. Has a level and shaft blocked by tram.
Also some references to copper and lead.

Info based on that received by Tony Oldham from Harold Morris. See linked CaMoA for diagram.

1. Rock-cut Steps
   A flight of steps has been carved into the rock cliff, leading down to a rock ledge situated just a few feet above the low tide mark.

2. Tunnel and Zawn Access
   From the rock ledge, an open cutting provides access to a tunnel. At point X, the tunnel runs straight and opens into a small zawn. It continues briefly on the far side before emerging onto the cliff face.
   To the west, the tunnel also extends in a straight line, though the roof height is reduced due to debris—stones and sand—deposited by the sea. This section leads to a T-junction. The southern branch ends after a few feet, while the northern branch opens into a natural fissure.

3. Mined-out Cave
   A large, excavated cave includes a raised step about 12 feet high located a few yards inside. At the back of the cave, a short climb leads to a short level passage.

4. Shaft in Cave Roof
   In the roof of the cave’s outer chamber, a vertical shaft breaks through to the surface. This shaft—identified as point Y—is obstructed by an old mining tram.

5. High Quarry Bench
   A quarry bench is located high on the cliff, split in two by a large rock outcrop. However, a narrow, vertical-sided cut connects both halves. The top of shaft Y is visible in the floor of the southernmost bench.

6. Sea-level Tunnel
   Another undeveloped tunnel exists at sea level. It can be accessed by carefully scrambling down a grassy rock slope beneath the quarry bench.

MJ 1875 p 603:

North Anglesey (Point Ælianus) Slate and Slab Quarry Company. Incorporated 1870 require £5000; £2300 to pay debts and £2700 to proceed. “Extraordinary large vein of pure blue slate, vertical face of 150 feet rising to 400 feet - 10 million cubic yards” [a good puff!]