Cap 1.5-3.0 cm broad, broadly parabolic to obtuse-conic, becoming campanulate to plano-convex, in age, margin upturned, torn, and deliquescent; surface glabrous to the unaided eye, minutely hairy viewed with a hand lens, striate-plicate at the margin, striations extending to near the disc, the latter buff-brown to dingy tawny-brown, shading to greyish-buff towards the margin; context thin, membranous; odor and taste not distinctive.
Gills crowded, narrowly adnexed, seceding, appearing free in age, less than 2 mm in width, pale-gray with blackish edges in youth, deliquescing, entirely black at maturity; lamellulae in up to three series.
Stipe 2-5 cm long, 1.5-3.0 mm in width, round, hollow, fragile, equal to slightly enlarged at the base; surface when young faintly pruinose to striate, translucent-grey; cottony fibrils at the base; partial veil absent.
Spores 9.0-11.5 x 7.0-7.5 µm, smooth, mitriform to heart-shaped in face-view, elliptical in profile, with a broad, truncate, central germ pore; spores blackish in deposit.
In small groups or clusters on burnt ground; fruiting in the spring in montane regions; occasional.
Edibility unknown; inconsequential.
Unusual for an inky cap, Coprinellus angulatus fruits in the charcoal debris left by forest fires, a habitat it shares with a number of burn-adapted species such as morels (Morchella spp), Pholiota highlandensis, Pachylepyrium carbonicola, Geopyxis carbonaria, Peziza violacea, etc. A helpful, though not definitive field character, is the lack of universal veil cap fragments, which differentiates it from species like Coprinopsis lagopus, Coprinellus flocculosus, and Coprinellus micaceus. Microscopically the presence of pileocystidia, also known as setules, and mitriform spores (shaped like a Bishop's cap) are additional identifying features. Coprinellus angulatus should be compared with Coprinellus disseminatus, a similar but smaller species which fruits in large troops, usually near decaying wood.