Castell Carn Dochan Mine

Overview

A small gold mine on the flanks of Ffridd Helyg y Moch near Llanuwchllyn, Gwynedd, taking its name from the ruined thirteenth-century castle, Castell Carn Dochan, on the crag directly above it. By far the most easterly mine of the Merioneth gold-mining area — some six miles from the better-known northern group around Gwynfynydd — it was the district's fourth most productive, worked in intermittent phases between 1862 and 1905 for gold recovered both as free milling grains in quartz and, more richly, from galena shoots in the same lode.

History

Gold fever struck the wider Dolgellau district in 1843, but it was not until 1862/63, when a 12-year-old shepherd boy noticed gold in rocks scattered across the hillside — some of it even built into field walls — that the deposit here was identified. Robert Roberts of the Clogau Mine, trading as Roberts & Co. with Captain Jeremiah Williams as local agent, worked the site through 1862 and 1863 with the Glanllyn Estate's permission but without Crown consent, prompting legal action from the Crown. The Manchester-based Carndochan Mining Company was formed in May 1863, chaired by John Bright MP with Thomas Readwin as secretary and Captain John Hughes as local agent. A shallow adit was driven into the lode and water from the Nant Ty Coch diverted to drive Britten and Mosheimer amalgamation pans; in its first year the company milled 1,103 tons of quartz for 747 ounces of gold. A larger mill followed in 1864, powered by a 50-foot waterwheel on the Afon Lliw, crushing ore through an eight-head stamp battery later enlarged to twenty heads. As working went deeper below the gossan the lode's increasing sulphide content began 'sickening' the mercury used in amalgamation, spoiling recovery; the company's secretary, Thomas Readwin, brought in the scientist William Crookes (later Sir William Crookes FRS), who developed a sodium-amalgam process to partly counter the problem. Full-scale work was abandoned in June 1866 as ore grade fell and the lode was lost against a fault; total recovery for 1863-66 was 2,254 ounces of gold from 4,268 tons of quartz. Captain Jeremiah Williams, the mine's first agent, died in January 1868 and is buried in Llanuwchllyn churchyard. Captain John Parry of the Clogau and Figra mines briefly revived working for the same company between 1869 and 1871, though the mineral statistics record no further milling after 1866; a petition to wind the company up was issued in 1873 and its plant sold the following year. The Cambrian Archaeological Association, visiting the adjacent castle ruin in 1885, noted the mine as abandoned. It was revived again in 1887, the company milling 50 tons of ore for 12.5 ounces of gold by 1889, and a further phase of work from 1894 kept the mine going on a small scale — 'a few ounces a week' — using a newly devised dry concentration process necessitated by a shortage of water; 393 ounces were recovered from 2,638 tons between 1895 and 1898. From 1898 the company concentrated on driving a deep adit (No. 4 Level), a costly undertaking that appears to have consumed most of its remaining capital; work tailed off and the mine finally closed in 1904 or 1905. Total recorded output across both main phases was 2,659.5 ounces of gold from 6,956 tons of quartz. The Glanllyn Estate forfeited its rights to the mine in 1947, offered in lieu of death duties, and the land and mineral rights were sold to the sitting tenants in the early 1960s. Later twentieth-century interest — a lease to Patrick Cheetham in 1980, a subsequent option taken up by Capital Resources, brief renewed fossicking by G.M.J. Gibourg in 1989-90, and a funding proposal from the Britannia Gold Company — never led to further working.

Geology

The lode is hosted by the Ordovician Nant Hir Mudstones. Although the mine lies within the wider Dolgellau Gold Belt, it is not a simple free-milling quartz-reef deposit: while some free gold occurs in the quartz, richer and more consistent grades of both gold and silver are carried in galena shoots within the same lode. The mudstones hosting the lode are known to persist to around 400 m below the mine's deepest adit, and no work was ever done below that level.

Workings

Worked from a series of adits, including a shallow adit driven in 1863 and a deep adit (No. 4 Level) begun after 1898. Ore was crushed through a stamp battery (enlarged over time from 8 to 20 heads) and treated by amalgamation in Britten and Mosheimer pans, later replaced by a dry concentration process when water became scarce.

Closure

Work wound down after 1898 as the company's capital was consumed driving the deep No. 4 Level adit; the mine appears to have finally ceased work in 1904 or 1905.

What remains

The mine sits immediately below the scheduled-monument ruins of Castell Carn Dochan, which occupy the crag above it. The Countryside Council for Wales has proposed the outcrop for SSSI designation, and the site carries further statutory protection as an Ancient Monument and as part of the Snowdonia National Park; any future work would have to be entirely underground.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Gold was noticed on the hillside by a 12-year-old shepherd boy in 1862/63; Roberts & Co. (Robert Roberts of the Clogau Mine) worked the site through 1862-63 without Crown consent, before the Manchester-based Carndochan Mining Company was formed in May 1863, chaired by John Bright MP. ¹
• In its first main phase of working, 1863-66, the company milled 4,268 tons of quartz for 2,254 ounces of gold, before full-scale work was abandoned in June 1866 as grades fell and the lode was lost against a fault. ¹
• As sulphide content increased with depth and began spoiling mercury amalgamation, secretary Thomas Readwin brought in the scientist William Crookes (later Sir William Crookes FRS), who developed a sodium-amalgam process to partly counter the problem. ¹
• The mine was revived in 1887 and again from 1894, recovering 393 ounces of gold from 2,638 tons of quartz between 1895 and 1898 using a dry concentration process necessitated by a shortage of water. From 1898 the company focused on driving a deep adit (No. 4 Level), and the mine finally closed in 1904 or 1905. Total output across both main phases was 2,659.5 ounces of gold from 6,956 tons of quartz, making it the 4th most productive mine in the Merioneth gold-mining district. ¹
• The lode, hosted in the Ordovician Nant Hir Mudstones, carries both free-milling gold in quartz and richer, more consistent gold and silver grades within galena shoots in the same lode. ¹
• The mine takes its name from Castell Carn Dochan, a ruined stone castle probably built in the early thirteenth century on the crag immediately above the mine, now a scheduled monument. ²
• The Glanllyn Estate forfeited its rights to the mine in 1947 in lieu of death duties, with land and mineral rights sold to sitting tenants in the early 1960s; later exploration interest (a 1980 lease to Patrick Cheetham, a Capital Resources option, brief renewed fossicking by G.M.J. Gibourg in 1989-90, and an unsuccessful funding proposal from the Britannia Gold Company) never led to further working. ¹

Sources

1. (secondary) Carn Dochan, Regional, General & Economic History (British Mining No.50, Memoirs 1994) — Northern Mine Research Society
2. (secondary) Carndochan Castle — Wikipedia

Record created: 26 August 2026 · Last researched: 26 August 2026