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New Roskear Shaft, Dolcoath Mine, Camborne, Cornwall, England, UK

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Latitude & Longitude (WGS84): 50° 13' 20'' North , 5° 17' 14'' West
Latitude & Longitude (decimal): 50.2224581881, -5.28735447675
UK National Grid Reference:SW653411
Other regions containing this locality:Devon and Cornwall metalliferous mining district, England, UK


In 1920, when further exploration of the bottom levels of Dolcoath Mine became unprofitable, the mine was abandoned and attention was directed to the Roskear section to the north, which had been acquired by the West Dolcoath Exploration Syndicate around 1898. In 1929, New Roskear shaft was sunk to a depth of 2,000 feet between the North and South Roskear main lodes, in order to explore the ground below the copper ore zone of these mines where rich tin ores were believed to exist.

From the surface, the shaft passed through greenstone (dolerite) and killas. Below 300 feet, a dark massive hornfels was cut, and below 620 feet, more greenstone was encountered which was invaded by small veinlets with weak tin or sulphide mineralization. Below 870 feet, it passed into hornfels again which then continued to full depth. It was only crossed by two narrow aplite veins, a pegmatite vein carrying some garnet, a granite vein and an elvan dyke. Lode fragments encountered at depths above 1,600 feet carried mainly chalcopyrite and sphalerite. Tin-bearing lodes hit below and in crosscuts driven at depths of 1,700 feet, 1,900 feet, and 2,000 feet gave extremely irregular assay values; high grade mineralizations were only met sporadically. After this work was completed, further capital was needed. Though, the lodes opened up were not encouraging enough and the project was abandoned.

Mineral List


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

Late Devonian
358.9 - 382.7 Ma
Upper Devonian Rocks (Undifferentiated)

Age: Late Devonian (358.9 - 382.7 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



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

- Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 1, pp. 282-284.

Mineral and/or Locality  
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