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Great Dowgas Mine (St Stephen Tin and Copper Mines), Downderry, St Stephen-in-Brannel, St Austell District, Cornwall, England, UK

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Latitude & Longitude (WGS84): 50° 19' 24'' North , 4° 52' 1'' West
Latitude & Longitude (decimal): 50.32333,-4.86694
UK National Grid Reference:SW959511
Other regions containing this locality:Devon and Cornwall metalliferous mining district, England, UK


A tin and copper mine which also produced pyrite, some cobalt and nickel ores and a considerable amount of ochre. It was first worked around 1719, when it sold some black tin, and reworked many times until 1913, but it was never very successful. In 1865, Thomas Spargo states that it "was always a poor mine, and the works have wholly ceased, at least underground, but the sett, I believe, has not been surrendered."

The mine worked five SE-trending lodes within a transverse distance of 130 fms, from north to south Woodhead's Lode, New North Lode, Copper Lode, Goffins Lode (or Coffins Lode, also known as Great Stopes Lode) and South Lode. It was drained by a deep adit, which commences near Coombe and follows the valley northeastwards to Brannel farm, where it turns to the southeast and continues into the sett of St Austell Consols, a distance of more than a mile. A cross-cut driven to the southwest below Dowgas farm connects to Engine Shaft, which was sunk on New North Lode, at 46 fms below surface. The grid reference marks the approximate position of this shaft. The engine house has not survived, but the stack is still standing.

Main lode was Goffins Lode, which was developed from several shafts on a length of 300 fms along strike. It occupied a crush zone and was composed of killas fragments and a filling of mainly quartz and pyrite. Cassiterite only occurred sporadically, except in the eastern part where the lode intersected an elvan before it passed into killas and died out. In the 18th century, the lode had already been worked from open gunnises, but they were abandoned at shallow depth, probably because the tin grades became poor.

The mine is reported to have sold some tin in 1719, but early production figures are not known. Up to 1832, it produced copper ores worth at least £12,000, and tin worth more than £9,000 is reported for the years 1828-1832. Official records give an output of 120 tons of black tin for 1856-1860, and another 47 tons for 1907-1913. In 1857, it also raised 4 tons of cobalt ores, but their mode of occurrence is not known. When it was worked for the last time, it mainly raised pyrite, which came from the upper levels. It finally closed in 1913.

During its last period of working, Great Dowgas Mine was amalgamated with Ventonwyn Mine. For some time during the 18th century, it also included Wheal Unanimity, which adjoined the sett on the east (not on the south, as suggested by Hamilton Jenkin; Beer, in: Dines, 1994). In 1873, it was worked for a short period of time together with parts of St Austell Consols under the name St Stephen Tin and Copper Mines.

Mineral List

Mineral list contains entries from the region specified including sub-localities

14 valid minerals.

Geochronology

Geologic TimeRocks, Minerals and Events
Phanerozoic
 Paleozoic
  Permian
   Guadalupian
ⓘ Major polymetallic mineralization~270 MaCornwall, England, UK
   Cisuralian
ⓘ Porphyry dikes intruded (latest age)~275 MaCornwall, England, UK
ⓘ Greisenization (latest age)~280 MaCornwall, England, UK
ⓘ Porphyry dikes intruded (earliest age)~280 MaCornwall, England, UK
ⓘ Formation of metallized pegmatites~285 MaCornwall, England, UK
ⓘ Greisenization (earliest age)~285 MaCornwall, England, UK
ⓘ Emplacement of major plutons~295 MaCornwall, England, UK

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Early Devonian
393.3 - 419.2 Ma
Lower Devonian Rocks (Undifferentiated)

Age: Early Devonian (393.3 - 419.2 Ma)

Lithology: Mudstone, siltstone and sandstone

Reference: British Geological Survey. DiGMapGB-625. British Geological Survey ©NERC. [23]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License


Localities in this Region

UK
  • England
    • Cornwall
      • St Austell District
        • St Stephen-in-Brannel
          • Downderry

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Henwood, W.J. (1843): On the Metalliferous Deposits of Cornwall and Devon. Transactions of the Royal Geological Society of Cornwall 5, 1-386.

Spargo, T. (1865): The Mines of Cornwall and Devon: Statistics and Observations. Victoria Press (London), 188 pp.

Collins, J.H. (1892): "A Handbook to the Mineralogy of Cornwall and Devon", 2nd ed., D. Bradford Barton Ltd. (Truro), 108 pp.

Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, pp. 544-545 (also see addenda and corrigenda in the 1994 reprint).

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