Thallus smooth or warted, grey but often with a green/brown tinge. Usually fertile, with apothecia to 2mm across with a black disc and a wide pale grey margin. Cutting through an apothecium shows the pale green interior. If the thallus is scratched, it usually reveals an orange pigment.
Chemistry: Thallus K+ yellow, P+ yellow/red, UV- or pale orange.
Similar species: Easily confused with Tephromela atra but cutting through an apothecium of T. atra shows a dark purple interior.
Common on siliceous rocks, especially near the sea, but also locally inland. More rarely found on worked wood.
Widespread but infrequent in central and south-eastern England.
Text by David Brabban & Maxine Putnam