With aging, many rocks surfaces not in direct contact with the soil, develop a black coating. This deposit has been given different names: desert varnish, rock varnish, and biogenic rock varnish. The rock varnish is a dark coating, usually 10 to 30 micrometers thick, with a variation from a few micrometers to over 500 micrometers. It is composed of manganese and iron oxides, silica, and clay minerals. A similar type of coating is accreted in pottery found in ancient tombs. The biological origin of the varnish was postulated in 1921 by Francis. Later, Dorn, and Dorn and Oberlander, described several bacterial groups, which were encapsulated in the rock varnish. Taylor-George, et al., and Staley et al. described microcolonial fungi MCF) that are able to deposit the different components of the varnish. One species of this MCF was successfully isolated and cultured, reported as Lichenothelia convexa. The components of a dark coating on an ancient green jasper carving from Southeast Mesoamerica were analyzed and compared to previous rock varnish analyses.