An ancient lead and silver mine, located about 1.2 km SW of Helston on the east side of the River Cober valley. The main lode, which is said to be the continuation of a cross-course that passes under Breage and along the eastern flank of Tregonning Hill, trends SE and crosses the valley at the northern end of Loe Pool. It was first worked from open casts and later from three shafts over a length of about 250 yards along its strike. Around 1800, the underground workings were 50 fathoms (92 m) deep. In driving south-eastwards, the lode was found to be heaved by a slide, beyond which it was not proved. Its continuation was not located until 1883 when exploration works were carried out at the mine. The sett also comprised another lode, which courses parallel to the main lode a little further north in the valley, and was worked to a depth of 34 fathoms.

In order to prevent the mine from drowning, the level of the water in Loe Pool was regulated by a drainage adit driven around 1790 from lake level through the cliffs at the southern end of the pool to the seashore. By doing this, the owners were able to remove up to 8 m of sediments and work up to 1.25 m of alluvial tin deposits. The outflow from the adit was used by tin streamers to work the tailings dumps of the mine.

The mine is said to have been active in the 16th century, but little is known about this early period of working. It possibly was started after the area had been exploited by the Company of Mines Royal in 1580. During another period of working around 1740, it yielded a tolerable profit to the adventurers. When it was set at work again around 1790, it produced lead ore which yielded from 30 to 40 ounces of silver per ton (60 ounces per ton according to Phillips, 1823), in a sufficient quantity to induce the proprietors to erect smelting and testing works for the extraction of silver. Yet the expense was so great as to absorb the principal part of the profit actually gained by working the mine, and the adventure was terminated a few years after (Carne, 1818). This was probably in 1796 because in that year, the owners of nearby Wheal Rose were looking at the Pool fire engine (Steam Beam Engine) with a view to purchase it for their mine. The next recorded working was in 1853, and it was prospected again in 1883 when test pits located the continuation of the lode south of the slide.

Geochronology

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

Other Regions, Features and Areas containing this locality

References