A mirror, in particular for a microlithographic projection exposure apparatus, has a mirror substrate (101), a reflection layer system (102) configured to reflect electromagnetic radiation that is incident on the optically effective surface (100a), and a capping layer (104), which is arranged on the side of the reflection layer system (102) facing the optically effective surface. The capping layer is produced from a first material. Particles (105) of a second material, either individually or in clusters, are applied onto this capping layer, wherein the second material differs from the first material.