Desert varnish

Desert varnish or rock varnish is an orange-yellow to black coating found on exposed rock surfaces in arid environments. Desert varnish is approximately one micrometer thick and exhibits nanometer-scale layering. Rock rust and desert patina are other terms which are also used for the condition, but less often.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.