Trelavour Downs
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Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| SW960574 | — | Unfavourable Recovering | 0.32 | 2011-01-24 |
Geology & landscape
Rock Type: Granite
Landscape processes: Volcanic / Igneous
Description
Trelavour Downs SSSI Description A shallow circular pit exposes the central quartz felspar portion of a pegmatitic body once worked for lithium. The selvages of the pegmatitie are of biotite rock, with crystals up to 0.15m in length. Recent trenching to explore the pegmatite further, has cut through the biotite selvage which at this point is 2-3 metres thick. Large lumps of solid biotite and coarse biotite pegmatite can be obtained from the working and the site is the best known locality for biotite mica in Britain. The pegmatite body is associated with the second intrusive phase of the Hercynian, St. Austell granite.