A striking, dark‑capped Agaricus recognised by its deep purplish‑brown to blackish cap, thick flesh.

Cap: 50-120 mm diam.; subglobose‑truncate when young, becoming convex with a broadly truncate centre, finally expanding and low‑mamelonate. Surface dark chocolate‑brown with a purplish sheen; densely covered in strong, appressed, plush‑like squamules. Margin overhanging and broadly appendiculate.
Gills: Free; fairly broad (6-8 mm), very crowded, acute at the ends. Initially pink, becoming cocoa‑brown. Edge entire, concolorous.
Stipe: 60-120 x 10-25 mm; stout, white, sometimes slightly bulbous at the base; Surface white, later pinkish at the apex; below the ring purplish‑brown, concolorous with the cap but paler and woolly‑squamulose; base white.
Ring: membranous, persistent, median; upper surface white and finely pruinose‑fibrillose; edge and lower surface with purplish‑brown squamules
Contex: White, weakly reddening then turning light chocolate‑brown. Odour absent