Some rocks according to their use or texture are classified into different types. Know more about Skarn Texture and Gossan Texture. Types of Skarn are Endoskarns whereas the types of Gossan are Translocated gossan and Leakage gossan.During historic times, some rocks depending on their hardness were used to create Pictographs and Petroglyphs. Rocks which are hard were generally not used. Pictographs are paintings or drawings that have been placed or created on the surface of rock. Skarn was not used to create pictographs whereas Gossan is used to create pictographs. Petroglyph is an image which is carved into a rock. These are images created by removing part of a rock surface by incising, picking, carving or abrading, as a form of rock art. Skarn was not used to create petroglyphs whereas Gossan was used to create petroglyphs.