Types of Tephrite and Coal
Some rocks according to their use or texture are classified into different types. Know more about Tephrite Texture and Coal Texture. Types of Tephrite are Not Available whereas the types of Coal are Peat, Lignite, Sub-Bituminous Coal, Bituminous Coal, Anthracite, Graphite.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. Tephrite and Coal 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. Tephrite and Coal were not used for creating petroglyphs.