Some rocks according to their use or texture are classified into different types. Know more about Essexite Texture and Oil shale Texture. Types of Essexite are Not Available whereas the types of Oil shale are Carbonate-rich Shale, Siliceous Shale and Cannel Shale.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. Essexite and Oil shale were not used for creating 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. Essexite and Oil shale were not used for creating petroglyphs.