Cae Coch Mine, Trefriw, Gwydyr Forest area, Conwy (Gwynedd; Caernarvonshire), Wales, UK

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The first reference to Cae Coch occurs in 1607; the mine being described as having a "great store of brimstone [Sulphur]". Much later, the mine was described as being "at a stand for twenty-five years until a new company came to investigate the prospect in 1817."

Production was on a small scale until the mine was acquired by Thompson & Hill to supply their new sulphur manufacturing works in Liverpool, the first pyrite being shipped in 1821. Initial production was about 20 tons/month and peaked at about 80 tons/month from 1834-43, after which it reduced to about 30 tons/month.

Between 1851 and June 1878, under new ownership, a little over 30,000 tons of pyrite was shipped to Liverpool (an output in most years of over a thousand tons).

In 1880 William Veitch, a chemical manufacturer from Scotland, who also had an interest in the Liverpool chemical industry (to where the pyrite continued to be sent), acquired the mine. Production peaked in 1885, when 119 men produced 9,443 tons of ore. Production remained steady until Veitch left in 1895, by which time 81,634 tons of pyrite had been extracted.

In 1889 ownership passed to the North Wales Sulphur Mining Company, who then abandoned their operations five years later. After this there were was little sustained production until the First World War when the Ministry of Munitions under the Defence of the Realm Act acquired the mine.

Exploratory work began in January 1917. By June, a workforce of 230 had constructed a power plant, installed compressors, and erected a crushing mill and aerial ropeway to carry the ore over the Conwy valley to the railway line. Between May and December 1918, 15,951 tons of pyrite was sent from the mine, just over half the total output from all UK mines. Production ceased in January 1919 and the mine then remained idle until the build up to the Second World War in 1939 when Cae Coch was again considered a potential source of sulphur.

Work to determine the reserves was started in August 1941 by the British (Non-Ferrous) Mining Corporation Limited, but the thickness and sulphur content of the pyrites proved inconsistent and the mine was closed in May 1942. However, sulphur continued in short supply for some time after the war, and Cae Coch was classified as an emergency reserve (although no further underground work was undertaken).

Finally, a two-year exploration licence was granted to John Taylor & Son in 1957, and British Titan Products drilled four boreholes in 1966. However, there was no follow-up by either company, no substantial reserves of pyrites having been found.

Ref: Mines of the Gwyder Forest, Part 7, John Bennett & Robert Vernon.

The Cae Coch ore body, a two metre thick bed of massive quartzitic pyrites is a major source of pyrites in Wales. The workings were accessed by four main adits; No. 1 accessed the northern ore body at the top of the hill whilst Nos. 2, 3 & 4 accessed the lower main southern ore body (No.2 adit accessed the extensive pillar and stall workings of the main mine whilst Nos. 3 & 4 were principally driven to drain the workings at depth).

There are still many surface remains at this site including the inclines, drum house, storage bins, mill foundations and other buildings. The No. 2 adit remains accessible and has some spectacular colouring in the rock although the mine water is now highly acidic, with acid pools that leave permanent stains on boots and clothing. The lower levels of the mine are flooded and are no longer accessible.

Mineral List

Copiapite Fibroferrite

Gypsum Jarosite

Melanterite Molybdenite

Pyrite Pyrrhotite

8 entries listed. 8 valid minerals.