Rhizocarpon ridescens (Nyl.) Zahlbr.

Syn.: Lecidea ridescens Nyl.
Lichenised.
Substrate: metal-rich siliceous rocks, siliceous rocks
Altitudinal range: from the montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies) to the nival belt (above the lower limit of perennial snow and glaciers)
Note: on iron-rich siliceous rocks, mostly under overhangs, with optimum near or above treeline; easily overlooked, being always sterile.
Austria: Vorarlberg; Tirol; Salzburg; Kärnten; Steiermark; Switzerland: Graubünden; Ticino; Valais; France: Alpes-de-Haute-Provence; Haute-Savoie; Italy: Friuli; Trentino Alto Adige; Lombardia; Piemonte;