Adit entrance The remains of an adit constructed in the early years of the 20th century with a view to extracting the silica-rich rhyolite rock for use as 'china stone', which was an additive for the production of high-quality porcelain ware. A common alternative was calcined flint, which was a pure silica. Fortunately, the activities caused great outrage, and the Town Council purchased the mineral rights to the mountain so that a recurrence was impossible.

About the year 1901-2 a person surnamed Carder made an attempt—fortunately an unsuccessful one, to exploit the lava rock, rhyolite, which constitutes much of the Moel Lus as the source of the silica it contains — a mineral needed as an ingredient in the making of pottery. He made a similar endeavour to exploit the same kind of rock forming Conwy Mountain where signs of his workings remain. On the Jubilee Walk he drove two tunnels, each penetrating six or seven yards into the rock — working a day and a night shift, and laid a rail track between the two tunnels. A bed for a self acting incline was prepared to reach down to behind Trwyn-y-Wylfa farm; it is plainly visible today. These operations, (there was blasting at night), aroused great anger locally. To prevent any such desecrations of the mountains in the future the District Council secured the mineral rights of the mountain common from the Crown authorities.

Copper - ore and manganese have been found in the parish, in small quantities, and pyrites in large masses ; but the copper mines only are now worked, and that upon a limited scale. There is also an abundance of feldspar, but the works have been nearly discontinued.