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Tregonning Hill, Breage, Cornwall, England, UKi
Regional Level Types
Tregonning HillHill
BreageCivil Parish
CornwallCounty
EnglandConstituent Country
UKCountry

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Latitude & Longitude (WGS84):
50° 7' 18'' North , 5° 21' 35'' West
Latitude & Longitude (decimal):
50.12168,-5.35974
GRN:
N34W03
Type:
Hill
Köppen climate type:
Cfb : Temperate oceanic climate
Nearest Settlements:
PlacePopulationDistance
Germoe175 (2017)1.5km
Breage471 (2017)2.4km
Leedstown267 (2017)4.3km
Porthleven3,059 (2017)5.1km
Helston12,184 (2017)6.7km
Mindat Locality ID:
38265
Long-form identifier:
mindat:1:2:38265:1
GUID (UUID V4):
0


A 1.2 m thick QFP elvan dyke in the Tregonning Hill area of SW Cornwall which was recently encountered during exploration drilling and shows particularly clear contact relations with its Mylor Slate host rocks. This lies approximately 1.7 km from the eastern margin of the Tregonning–Godolphin granite within low grade regionally metamorphosed Devonian mudstones, siltstones, and sandstones of the Mylor Slate Formation. The Tregonning–Godolphin granite pluton comprises the earlier Godolphin two-mica G1 granite, which is variably porphyritic and fine-grained, and the petrogenetically distinct Tregonning granite, which is a fine-medium-grained, equigranular, Li-enriched G5 granite.
Stage I in the QFP, which was magmatic, involved the emplacement of felsic magma and crystallisation of K-feldspar (Kfs 1) and quartz (Qz 1) phenocrysts. Stage II in the QFP produced quartz veining with associated polymetallic mineralisation and proximal potassic alteration selvages around the veins and as isolated (non-vein-related) patches elsewhere. Stage II also caused the replacement of albite in the QFP groundmass and micas in the SWR with K-feldspar (Kfs 2) to produce the WZ. Stage III caused widespread sericitisation which post-dates the Stage I and II K-feldspar, which it occasionally cross-cuts or replaces. It produced blocky fine sericite (0.1–0.2 mm) and comparatively coarser (up to 0.5 mm) flakes of sericite (Figure 8b,c), which occasionally pseudomorph Stage II K-feldspar. Stage IV involved kaolinisation of Stage I K-feldspar phenocrysts, Stage II K-feldspar, and Stage III sericite. Stage III sericite is also locally replaced by smears and ragged, irregular <0.1 mm Fe-rich pinite, possibly of chlorite or illite. Fe (Mn) oxide, in turn, overprints kaolinised Stage I K-feldspar and occurs as a fracture infill of Stage I and II quartz.

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Standard Detailed Gallery Strunz 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

13 valid minerals.

Rock Types Recorded


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

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Albite
Formula: Na(AlSi3O8)
ⓘ 'Apatite'
Formula: Ca5(PO4)3(Cl/F/OH)
ⓘ Arsenopyrite
Formula: FeAsS
ⓘ 'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ Cassiterite
Formula: SnO2
ⓘ Chalcopyrite
Formula: CuFeS2
ⓘ 'Chlorite Group'
ⓘ 'Columbite Group'
ⓘ Cordierite
Formula: Mg2Al4Si5O18
ⓘ 'Feldspar Group'
ⓘ Fluorapatite
Formula: Ca5(PO4)3F
ⓘ Galena
Formula: PbS
ⓘ 'Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series'
ⓘ Kaolinite
Formula: Al2(Si2O5)(OH)4
ⓘ 'K Feldspar'
ⓘ 'Lepidolite'
ⓘ Muscovite
Formula: KAl2(AlSi3O10)(OH)2
ⓘ Muscovite var. Illite
Formula: K0.65Al2.0[Al0.65Si3.35O10](OH)2
ⓘ Muscovite var. Sericite
Formula: KAl2(AlSi3O10)(OH)2
ⓘ 'Pinite'
ⓘ Pyrite
Formula: FeS2
ⓘ Quartz
Formula: SiO2
ⓘ Sphalerite
Formula: ZnS
ⓘ 'White mica'
ⓘ Zircon
Formula: Zr(SiO4)

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
ⓘSphalerite2.CB.05aZnS
ⓘChalcopyrite2.CB.10aCuFeS2
ⓘGalena2.CD.10PbS
ⓘPyrite2.EB.05aFeS2
ⓘArsenopyrite2.EB.20FeAsS
Group 4 - Oxides and Hydroxides
ⓘ'Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series'4..
ⓘQuartz4.DA.05SiO2
ⓘCassiterite4.DB.05SnO2
Group 8 - Phosphates, Arsenates and Vanadates
ⓘFluorapatite8.BN.05Ca5(PO4)3F
Group 9 - Silicates
ⓘZircon9.AD.30Zr(SiO4)
ⓘCordierite9.CJ.10Mg2Al4Si5O18
ⓘMuscovite
var. Illite		9.EC.15K0.65Al2.0[Al0.65Si3.35O10](OH)2
ⓘ9.EC.15KAl2(AlSi3O10)(OH)2
ⓘvar. Sericite9.EC.15KAl2(AlSi3O10)(OH)2
ⓘKaolinite9.ED.05Al2(Si2O5)(OH)4
ⓘAlbite9.FA.35Na(AlSi3O8)
Unclassified
ⓘ'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ'Chlorite Group'-
ⓘ'Feldspar Group'-
ⓘ'Lepidolite'-
ⓘ'Pinite'-
ⓘ'K Feldspar'-
ⓘ'Apatite'-Ca5(PO4)3(Cl/F/OH)
ⓘ'Columbite Group'-
ⓘ'White mica'-

List of minerals for each chemical element

HHydrogen
Hⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Hⓘ Muscovite var. IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Hⓘ KaoliniteAl2(Si2O5)(OH)4
Hⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Hⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Hⓘ ApatiteCa5(PO4)3(Cl/F/OH)
OOxygen
Oⓘ AlbiteNa(AlSi3O8)
Oⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Oⓘ CassiteriteSnO2
Oⓘ CordieriteMg2Al4Si5O18
Oⓘ FluorapatiteCa5(PO4)3F
Oⓘ Muscovite var. IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Oⓘ Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series
Oⓘ KaoliniteAl2(Si2O5)(OH)4
Oⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Oⓘ QuartzSiO2
Oⓘ ZirconZr(SiO4)
Oⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Oⓘ ApatiteCa5(PO4)3(Cl/F/OH)
FFluorine
Fⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Fⓘ FluorapatiteCa5(PO4)3F
Fⓘ ApatiteCa5(PO4)3(Cl/F/OH)
NaSodium
Naⓘ AlbiteNa(AlSi3O8)
MgMagnesium
Mgⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Mgⓘ CordieriteMg2Al4Si5O18
AlAluminium
Alⓘ AlbiteNa(AlSi3O8)
Alⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Alⓘ CordieriteMg2Al4Si5O18
Alⓘ Muscovite var. IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Alⓘ KaoliniteAl2(Si2O5)(OH)4
Alⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Alⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SiSilicon
Siⓘ AlbiteNa(AlSi3O8)
Siⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Siⓘ CordieriteMg2Al4Si5O18
Siⓘ Muscovite var. IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Siⓘ KaoliniteAl2(Si2O5)(OH)4
Siⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Siⓘ QuartzSiO2
Siⓘ ZirconZr(SiO4)
Siⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
PPhosphorus
Pⓘ FluorapatiteCa5(PO4)3F
Pⓘ ApatiteCa5(PO4)3(Cl/F/OH)
SSulfur
Sⓘ ArsenopyriteFeAsS
Sⓘ ChalcopyriteCuFeS2
Sⓘ GalenaPbS
Sⓘ PyriteFeS2
Sⓘ SphaleriteZnS
ClChlorine
Clⓘ ApatiteCa5(PO4)3(Cl/F/OH)
KPotassium
Kⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Kⓘ Muscovite var. IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Kⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Kⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
CaCalcium
Caⓘ FluorapatiteCa5(PO4)3F
Caⓘ ApatiteCa5(PO4)3(Cl/F/OH)
TiTitanium
Tiⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
MnManganese
Mnⓘ Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series
FeIron
Feⓘ ArsenopyriteFeAsS
Feⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Feⓘ ChalcopyriteCuFeS2
Feⓘ Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series
Feⓘ PyriteFeS2
CuCopper
Cuⓘ ChalcopyriteCuFeS2
ZnZinc
Znⓘ SphaleriteZnS
AsArsenic
Asⓘ ArsenopyriteFeAsS
ZrZirconium
Zrⓘ ZirconZr(SiO4)
SnTin
Snⓘ CassiteriteSnO2
TaTantalum
Taⓘ Ixiolite-(Mn2+)-Ixiolite-(Fe2+) Series
PbLead
Pbⓘ GalenaPbS

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

Localities in this Region

UK

Other Regions, Features and Areas containing this locality

British and Irish IslesGroup of Islands
Eurasian PlateTectonic Plate
EuropeContinent
UK

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

[1]Penfound-Marks, Louis R. G.; Williamson, Ben J.; Rollinson, Gavyn K.; Shail, Robin K. (2026) Potassic Metasomatism of Slate Wall Rock and Polymetallic Mineralisation Associated with the Intrusion of a Quartz–Feldspar Porphyry Dyke in the Tregonning Hill Area of Southwest England. Minerals, 16 (4). 368 doi:10.3390/min16040368
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