St Austell Clay Pits, (Cornwall, England, UK,) are a group of locations within active china clay quarries that form a single Site of Special Scientific Interest (SSSI) and Special Area of Conservation, noted for its biological characteristics.

The 0.6-hectare (1.5-acre) SSSI, notified in 2000, comprises three separate sites that are all about 4 miles (6.4 km) north of the town of St Austell.

[1][2] They all lie within china clay workings which are still active and are situated on either pits, spoil tips or vegetation-covered granitic debris.

[4] The SSSI owes its importance to a rare liverwort, the western rustwort (Marsupella profunda), which in the UK can be found only at this site and at two others: Lower Bostraze and Leswidden and Tregonning Hill SSSIs, both within Cornwall, to the west.

It is mostly found growing in moist conditions on micaceous or clay waste substrates with no or little sloping, as well as on soft or crumbling granite rocks.