Chalcocite

specimen number:
2102247

location:
Tresevean Mine, Camborne, Cornwall, England, UK

description:

Lustrous metallic crystals of chalcocite averaging 0.3 cm in size across the top of matrix. These are bright, sharp, and in very good condition. Ex John Gliddon collection with label as shown at the end of the video.

The Tresavean Mine, situated near Lanner and Camborne in the Gwennap mining district of Cornwall, England, was one of the most famous and deepest copper producers in the region. Geologically, the mine exploited a series of rich hydrothermal veins, or lodes, that cut through the Carnmenellis granite and surrounding killas (metasedimentary rocks), with the Main Lode being particularly celebrated for its immense width and high-grade copper content. The mine is a classic locality for chalcocite, which occurred here in significant masses and as well-formed, dark gray to black metallic crystals, often as a primary mineral in the deep copper zones. Historically, while mining in the area dates back centuries, Tresavean reached its peak of fame in the early to mid-19th century, notably installing the first "man engine" in Cornwall in 1842 to transport miners to depths exceeding 2,000 feet. The mine saw several periods of activity, with its most productive era ending in the 1870s, followed by a major but ultimately unsuccessful attempt at reworking for tin between 1907 and 1928. Today, it is remembered as a marvel of Victorian mining engineering and a source of some of the finest historical chalcocite specimens from the Cornish copper boom.

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