Tresayes Quarry (Polpuff Quarry), Trezaise (Tresayes), Roche, St Austell District, Cornwall, England, UK
|Latitude & Longitude (WGS84):||50° 23' 45'' North , 4° 49' 27'' West|
|Latitude & Longitude (decimal):||50.39583,-4.82417|
|UK National Grid Reference:||SW993590|
|Other regions containing this locality:||Devon and Cornwall metalliferous mining district, England, UK|
|Köppen climate type:||Cfb : Temperate oceanic climate|
A disused quarry in a pegmatite known for its large feldspar crystals. First opened in the late 1870s, the Mining Journal records that production was hampered by severe winters on this exposed common. Early production was for pure feldspar which was used for making glass and the quarry was known locally as the glass mine. Although worked mainly as a quarry there are reputed to be underground workings.
The quarry was re-opened in 1917, during the First World War, to provide feldspar for electrical porcelain. It closed again shortly afterwards.
Cornwall Wildlife Trust manage the quarry. Until very recently, the dense vegetation combined with very damp conditions made it impossible to access the quarry. The quarry is managed on the remaining part of a 25 year lease from Goonvean China Clay Company.
After studying the exposure, when you return to your car, you will spot low grade ore samples in the unmade road. Only the purest feldspar was used and the rest treated as waste.
2 valid minerals.
|Geologic Time||Rocks, Minerals and Events|
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
323.2 - 358.9 Ma
|Paleozoic sedimentary rocks|
Age: Mississippian (323.2 - 358.9 Ma)
Lithology: Sedimentary 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. 
393.3 - 419.2 Ma
|Lower Devonian Rocks (Undifferentiated)|
443.8 - 485.4 Ma