Thallus areolate, discontinuous; hypothallus indistinct; areolae up to 0.8 mm diam., pale grey, slightly shiny, scattered, orbicular to angular, plane to weakly convex; medulla KI–. – Apothecia up to 0.6 mm diam., black, epruinose, orbicular, plane to weakly convex, with a narrow and distinct margin; excipulum brownish black in the rim, inner part paler brown, lacking crystals, K+ red; hypothecium brown, K–; hymenium colourless, containing crystals dissolving in K; epihymenium dark brown, K+ red; ascospores 8 per ascus, 1-septate, persistently colourless, 9–12 × 4–6 µm. – Conidiomata not seen.
Norstictic acid; spot tests: medulla PD+ yellow, K+ red, C–.
On siliceous rock in the mountains.
In Norway the species is known from a single locality at 2468 m alt. (Degelius 1948). The description is based on the Swedish holotype. Rhiocarpon cinereovirens differs in having a greenish (K–) epihymenium and larger ascospores.