Some rocks according to their use or texture are classified into different types. Know more about Ganister Texture and Variolite Texture. The types of Ganister and Variolite are Not Available.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. Ganister was not used to create pictographs whereas Variolite 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. Ganister was not used to create petroglyphs whereas Variolite was used to create petroglyphs.