A crustose species with a grey to light ochre thallus. The thallus can be smooth or cracked and has no, or only a weak, prothallus. The black apothecia are more or less flat and have a thick, paler, persistent margin.
In Scotland, Rhizocarpon lavatum is particularly widespread in upland regions where it grows on siliceous rocks that are flushed or frequently inundated by unpolluted streams and lochs. BLS distribution map
scottishlichens.co.uk 