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Great Dowgas Mine (St Stephen Tin and Copper Mines), Downderry, St Stephen-in-Brannel, Cornwall, England, UKi
Regional Level Types
Great Dowgas Mine (St Stephen Tin and Copper Mines)Mine
Downderry- not defined -
St Stephen-in-Brannel- not defined -
CornwallCounty
EnglandConstituent Country
UKCountry

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Key
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Latitude & Longitude (WGS84):
50° 19' 24'' North , 4° 52' 1'' West
Latitude & Longitude (decimal):
UK National Grid Reference:
SW959511
Locality type:
Köppen climate type:
Nearest Settlements:
PlacePopulationDistance
Saint Stephen2,252 (2015)3.3km
Grampound537 (2017)3.6km
Nanpean2,563 (2017)5.1km
Saint Dennis2,206 (2016)6.8km
St Austell25,447 (2017)6.9km


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.

Regions containing this locality

Eurasian PlateTectonic Plate
EuropeContinent
British IslesGroup of Islands
Devon and Cornwall metalliferous mining district, England, UKMining District
St Austell Mining District, Cornwall, England, UKMining District

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

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

14 valid minerals.

Detailed Mineral List:

Actinolite
Formula: ☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Reference: Henwood, W.J. (1843): Transactions of the Royal Geological Society of Cornwall 5, 1-386; Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
Arsenopyrite
Formula: FeAsS
Reference: Jones, W.R. (1925): Tinfields of the World. Mining Publications Ltd. (London), 423 pp.
Bismuth
Formula: Bi
Reference: Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.; Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, pp. 544-545
Bismuthinite
Formula: Bi2S3
Reference: Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.; Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, pp. 544-545
Cassiterite
Formula: SnO2
Chalcopyrite
Formula: CuFeS2
Reference: Henwood, W.J. (1843): Transactions of the Royal Geological Society of Cornwall 5, 1-386; Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.
'Chlorite Group'
Reference: Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, p. 545
Copper
Formula: Cu
Reference: Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
Fluorite
Formula: CaF2
Reference: Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.; Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, pp. 544-545
Gold
Formula: Au
Reference: Rudler, F.W. (1905): A Handbook to a Collection of the Minerals of the British Islands, Mostly Selected from the Ludlam Collection. HMSO Publications (London), 241 pp.
'Hornblende'
Reference: Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
Kaolinite
Formula: Al2(Si2O5)(OH)4
Reference: Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
'Limonite'
Formula: (Fe,O,OH,H2O)
Reference: Rudler, F.W. (1905): A Handbook to a Collection of the Minerals of the British Islands. HMSO Publications (London), 241 pp.
'Ochre'
Reference: Dines, H.G. (1956): The metalliferous mining region of south-west England. HMSO Publications (London), Vol. 2, pp. 544-545.
Pyrite
Formula: FeS2
Reference: Henwood, W.J. (1843): Transactions of the Royal Geological Society of Cornwall 5, 1-386; Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
Quartz
Formula: SiO2
Reference: Henwood, W.J. (1843): Transactions of the Royal Geological Society of Cornwall 5, 1-386.
Schorl
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Reference: Henwood, W.J. (1843): Transactions of the Royal Geological Society of Cornwall 5, 1-386; Hall, T.M. (1868): The Mineralogist's Directory. Edward Stanford (London), 168 pp.; Collins, J.H. (1871): A Handbook to the Mineralogy of Cornwall and Devon. D. Bradford Barton Ltd. (Truro, UK), 108 pp.
Siderite
Formula: FeCO3
Reference: Rudler, F.W. (1905): A Handbook to a Collection of the Minerals of the British Islands. HMSO Publications (London), 241 pp.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Bismuth1.CA.05Bi
Copper1.AA.05Cu
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Arsenopyrite2.EB.20FeAsS
Bismuthinite2.DB.05Bi2S3
Chalcopyrite2.CB.10aCuFeS2
Pyrite2.EB.05aFeS2
Group 3 - Halides
Fluorite3.AB.25CaF2
Group 4 - Oxides and Hydroxides
Cassiterite4.DB.05SnO2
Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Siderite5.AB.05FeCO3
Group 9 - Silicates
Actinolite9.DE.10☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Kaolinite9.ED.05Al2(Si2O5)(OH)4
Schorl9.CK.05Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Unclassified Minerals, Rocks, etc.
'Chlorite Group'-
'Hornblende'-
'Limonite'-(Fe,O,OH,H2O)
'Ochre'-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Copper1.1.1.3Cu
Gold1.1.1.1Au
Semi-metals and non-metals
Bismuth1.3.1.4Bi
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 2:3
Bismuthinite2.11.2.3Bi2S3
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Pyrite2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
AX2
Cassiterite4.4.1.5SnO2
Group 9 - NORMAL HALIDES
AX2
Fluorite9.2.1.1CaF2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Siderite14.1.1.3FeCO3
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with borate groups
Schorl61.3.1.10Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
Actinolite-☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
'Chlorite Group'-
'Hornblende'-
Kaolinite-Al2(Si2O5)(OH)4
'Limonite'-(Fe,O,OH,H2O)
'Ochre'-

List of minerals for each chemical element

HHydrogen
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
H Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
H KaoliniteAl2(Si2O5)(OH)4
H Limonite(Fe,O,OH,H2O)
BBoron
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
CCarbon
C SideriteFeCO3
OOxygen
O CassiteriteSnO2
O QuartzSiO2
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
O KaoliniteAl2(Si2O5)(OH)4
O SideriteFeCO3
O Limonite(Fe,O,OH,H2O)
FFluorine
F FluoriteCaF2
NaSodium
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
MgMagnesium
Mg Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
AlAluminium
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Al KaoliniteAl2(Si2O5)(OH)4
SiSilicon
Si QuartzSiO2
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Si KaoliniteAl2(Si2O5)(OH)4
SSulfur
S BismuthiniteBi2S3
S PyriteFeS2
S ChalcopyriteCuFeS2
S ArsenopyriteFeAsS
CaCalcium
Ca FluoriteCaF2
Ca Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
FeIron
Fe PyriteFeS2
Fe ChalcopyriteCuFeS2
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Fe Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Fe ArsenopyriteFeAsS
Fe SideriteFeCO3
Fe Limonite(Fe,O,OH,H2O)
CuCopper
Cu CopperCu
Cu ChalcopyriteCuFeS2
AsArsenic
As ArsenopyriteFeAsS
SnTin
Sn CassiteriteSnO2
AuGold
Au GoldAu
BiBismuth
Bi BismuthBi
Bi BismuthiniteBi2S3

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

Permian
251.902 - 298.9 Ma



ID: 3186762
Paleozoic intrusive rocks

Age: Phanerozoic (251.902 - 298.9 Ma)

Lithology: Intrusive igneous rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Devonian
358.9 - 419.2 Ma



ID: 3135951
Devonian claystone

Age: Devonian (358.9 - 419.2 Ma)

Lithology: Claystone

Reference: Asch, K. The 1:5M International Geological Map of Europe and Adjacent Areas: Development and Implementation of a GIS-enabled Concept. Geologisches Jahrbuch, SA 3. [147]

Early Devonian
393.3 - 419.2 Ma



ID: 2033471
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

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
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).

External Links


Localities in this Region
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  • England
    • Cornwall
      • St Stephen-in-Brannel
        • Downderry

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