Cap 1.5 to 4 cm across, conical then expanded and umbonate, dark brown when moist, especially at the centre, drying yellow brown, surface silky matt, with a pale edge. It has a characteristic earthy smell like beetroot (with a hint of rhubarb). 

other Cortinarius

microscope/smell

Identification is very difficult, requiring microscopic examination.  If you have not done this or if the specimen has not been examined by an expert, please submit your record as genus only (Cortinarius); and note habitat and smell

Damp places with deciduous trees, and often with birch.

Autumn.

Widespread but infrequent in Britain.

Infrequent in Leicestershire and Rutland.