Underground with drainage level near Llanllechid Church. Some remains on site.**

Several reused buildings, one carrying a slate sign for the Bangor Slate Co., and a large volume of tipped waste constrained within the tight working area, along with the abutments of two former rubbish‑run bridges. The original pit has partly run in, masking former adits and haulage routes, but a substantial engine house survives beside the filled, stone‑lined haulage shaft, , while the exact location of the second engine—likely used to power saws—remains uncertain and a stockyard still contains stacks of finished slate.

This quarry was the only major underground slate working in Caernarfonshire, established around 1805 and worked intermittently until 1911. Early operations involved hauling rock from an open pit to a small surface mill, but later phases expanded underground and used a vertical shaft for haulage, with two steam engines whose costs reportedly harmed profitability. The cramped nature of the site created persistent waste‑tipping problems, annual output probably never exceeded about 500 tons, and although finished slate was first carted away, it was later sent out via Moel Faban’s exit incline when the two sites were worked together, with a drainage level said to emerge near the church at Llanllechid.