rock coatings Approximately one-sixth of the Earth's land surface consists of ‘bare’ rock surfaces. Yet the true mineral faces of the rock are rarely seen. Instead, a variety of paper-thin accretions coat rocks in all terrestrial environments. Since weathering includes the formation of new compounds that are more in equilibrium with the environment at and near the Earth's surface, rock coatings fall under the interdisciplinary field of weathering. Intellectual curiosity about the physical and chemical characteristics, origin, geography, and utility of these encrustations has spawned over 3000 scientific papers. A wide variety of rock coatings is found on landforms at ...