Monday, 3 August 2015

In search of Dolcoath- Cornwall's greatest mine

The photograph below was taken in the early 1890s by the great Cornish mining photographer J.C. Burrow (posting of 25 May). It shows the extent of the mining activity on the north side of Carn Brea Hill, between Camborne and Redruth, as seen looking east from the top of the north stamps engine-house of the 'Queen of Cornish Mines' Dolcoath.


Dolcoath Mine started work for copper during the 1720s and of around 470 copper-producing mines in Cornwall and Devon, it became the fifth largest. But as depth increased the copper died out, and by 1832 the mine was in danger of closing. However tin ore was found deeper down at 1250 feet and the mine became the largest producer of tin in western England, reaching an output of 2000 tons per year in 1884. However by 1896 this had reduced to 1160 tons, and from 1912 it fell rapidly to only 400 tons in 1918.

Dolcoath was particularly famous for its depth, "as deep as Dolcoath" being a familiar Cornish expression to indicate anything of great depth. By 1882 the mine had reached a depth of 2,160 feet and had 12 miles of tunnels. In 1895 it took men employed in the lower levels between 2-3 hours to go down and return to the surface, so they could not work more than 4-5 hours a day. A new shaft, the Williams Shaft, was started in October 1895, intended to be the first 3,000-foot vertical shaft in Cornwall. It was completed in 1910 and came into use the next year and the mine became the largest and deepest in Cornwall, and the world's deepest tin mine, eventually reaching a depth of 3,300 feet below the surface.

In 1920 when the mine had become virtually worked out and following the tin price collapse (new deposits were also being found elsewhere in the world) Dolcoath finally closed. Like many Cornish miners, the men were in great demand for their hard rock mining expertise, and many of these "Cousin Jacks" took their skills to the new mines of North America, Australia and the gold mines of the Witwatersrand, hardly imagining that around 100 years later deep mining would mean anything up to 12,800 ft (3.9 km) in depth!

Contrast the scene in Burrow's 19th century photograph with that today from a similar but lower viewpoint, as there is now no trace of the stamps engine house. In fact very little now remains of the once intensive tin mining operations in this area, the head-gear on the left being that of South Crofty, the last mine to close in 1998, and the ruined engine house in the centre is Tincroft, which can be seen in Burrow's photo.


Harriett's Shaft
Much of the area is now derelict or taken over by housing and industrial development, and very few engine houses or shafts now remain. One of the best preserved is Harriett's Shaft Engine House, which served as a pumping house, and also for winding man-riding skips which replaced the famous Dolcoath man-engine in 1897. Nothing now remains of the nearby man-engine, which was installed in 1854 and reached a depth of nearly 1500 ft (see also posting of 25 May).

Further south, and almost hidden in dense undergrowth, are the remains of Williams' Shaft, Cornwall's deepest vertical shaft, sunk between 1895 and 1910 to meet the Dolcoath main lode.


The overgrown ruins of Williams' Shaft engine house
But nothing now remains of the once extensive dressing floors which upgraded the mined ore to produce cassiterite, or 'black tin' concentrates. The photo below shows Dolcoath's extensive use of rag frames, which were used to recover small amounts of tin from very fine material, or slimes, which were in the tailings of the buddle concentrators.

Rag frames at Dolcoath
Rag frames were simple machines comprising a wooden deck inclined at a shallow angle. The feed pulp was distributed by a board and flowed evenly down the deck where the heavier particles settled whilst the lighter material passed over a hinged tailboard and flowed to a tailing launder. Positioned above the deck was a wooden box held within a pivoted tilting frame. Water continually flowed into this box, and when full, it tipped over cascading the water over the deck to wash off the deposited material. This was deflected into a separate parallel launder by the tailboard, which was momentarily raised by the tipping water box/ tilting frame. After a few seconds the now empty box returned to its original position to start the cycle again. Many hundreds of rag frames would be linked together to form a “slimes plant” and would have been a common surface feature on many 19th and early 20th century Cornish mines. Being made entirely of wood, nothing remains of these ingenious devices, and the only place where they can now be seen in action is at the King Edward Mine Museum in Camborne.

Rag Frames at King Edward Mine Museum
Incidentally, I had always wondered why Dolcoath was always described as the world's deepest tin mine, not the world's deepest mine. In 1882 it had reached a depth of 2160 feet, so what was the world's deepest mine at that time? I was amazed when I Googled and discovered that in 1882 the world's deepest mine was in the north of England, near Manchester, in a small cotton milling town called Ashton-under-Lyne, and the mine was the Ashton Moss Colliery, with a depth of 2850 ft.

Not only was I amazed by this, I was also totally flabbergasted, as Ashton-u-Lyne was where I was born and raised, and for most of my early life prior to going to University I lived with my parents on the Ashton Moss council estate, only about a mile from this mine, which we knew as the Snipe Pit, and which closed down in 1959. I was well aware that Ashton was a cotton milling town, as the old mills dotted the landscape very much like the mining engine houses dot the landscape of Cornwall, and my mother and grandmother had worked in the cotton mills. But I was unaware that in the 19th century the town also had several deep coal mines, of which Ashton Moss was just one. Now, rather like Dolcoath, very little evidence remains- the site of the Ashton Moss mine is now a large retail park, and the only legacy is the nearby pub, the Snipe Inn, one of my many watering holes during my late teens!

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