The 1850s also saw the rise of another important producer, Swanpool, while the 1860s saw the emergence of West Chiverton, Cargol and Ludcot, all located in the west of the county. However, these mines could not compensate for the declining fortunes of Mary Anne and Trelawney in the mid-1860s and although there was some overall surge in output at the end of the decade, based on a burst of production from West Chiverton, serious decline was evident from the early 1870s. The fall in lead prices after 1873 greatly increased the industry's difficulties and a further fall in the 1880s virtually finished it off. Taking the period 1845 1913 as a whole, around 170 Cornish mines sold some quantity of lead ore. Just five of these mines -- East Wheal Rose, West Chiverton, Mary Anne, Trelawney and Herodsfoot -- accounted for over two thirds of total production. When their lodes began to run out, none were found to replace them.
Similarly, at the peak of its output in 1870, West Chiverton produced 3,582 tons of lead which was estimated to contain over 160,000 oz. of silver, eg. 45 oz. to the ton. With refining becoming profitable at anything over 5 oz. per ton, this represented a very considerable extra income to the mine. Again the values of the lead and silver contents of the ores were very similar, at about £40,000 each. However, some caution must be exercised in using these calculations. Although the proportionate importance of the various minerals probably remained the same, it must be emphasised that the mines did not receive the full market values of the ores that they produced. Clearly allowance was made for transport, reduction, refining and other processing costs. For example, in 1873 West Chiverton sold 2,224 tons of lead ore with an estimated lead content of 1,668 tons of lead and 70,056 oz. of silver. The average price of lead in that year was £15-8-0 per ton and silver stood at about five shillings an ounce. This would suggest a potential market value for the metals of £43,201. However, the mine received only £29,929, with the other third of market value going to the merchants and manufacturers. On this estimate the mines received only just over two thirds of the market value of the metals they produced, the remainder going to the merchants and manufacturers.
The production of zinc was less significant for Cornwall's lead mines than silver. Only around 45 mines produced the two metals in combination during the period and many of these had very low levels of lead output and made no important contribution to that industry. West Chiverton and Cargol were the only important lead producers to achieve a high level of zinc output and even here the main productive period was comparatively short. However, zinc sales undoubtedly made a very major contribution to Cargol's total income as its lead production fell off in the 1860s and it briefly kept the mine alive and profitable. Similarly, zinc production first grew in importance and then took over as the primary product of West Chiverton in the 1870s and significantly extended the life of Cornwall's second largest lead producer. In those years it became one of Britain's largest zinc mines. The supportative influence of zinc production was less diffuse than silver and concentrated in a shorter period but it undoubtedly played a crucial role in the lives of some mines.
With the exception of West Chiverton and Cargol, most of Cornwall's zinc came from mines other than lead mines, produced either alone or in association with copper, tin, iron and other minerals. Over 50 mines fell into this categor
The sudden surge of output from West Chiverton in the late 1870s, powerfully supported by that from Duchy and Peru in the early 1880s, revitalised the industry. It carried Cornish zinc output to an all-time peak during those years and it became the largest single county producer, contributing up to a fifth of total national output. However, new producers in Wales, Cumberland and the Isle of Man were also expanding their operations and soon resumed the lead. With the closure of West Chiverton and Duchy and Peru in the mid-1880s, Cornish zinc production collapsed and rarely again amounted to more than a few hundred tons per year.
This 26-inch engine was bought from West Chiverton Mine in 1881for £220 to wind from the shaft adjacent to the pumping engine.
Mines on the North Cornwall Coast