Pileus: convex; 20 - 70 mm diameter; viscid to glutinous, weakly or not hygrophanous; umber to blackish brown with a faint, purple tinge; coarsely innate fibrillose or granulose, often with sparse, grey to pale ochre patches ortufts; margin violet, when mature striate to rimose, often denticulate.

Gills: saturated violet, immutable on pressure.

Stipe: cylindrical to clavate; brilliantly lilac-blue, partly coated silverypale violet, immutable on pressure, with thin, violaceous fibrils and bands; apex pale blue to white.

Flesh: persistently violet.

Spore print: rusty brown.                       

Spores: elliptic to subamygdaloid; 8 - 10 ×5.5-6.5 μm, rather coarsely verrucose.

Notes: this Cortinarius is like the New Zealand species C. chalybaeus.