Know all about Gritstone and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Gritstone belongs to Sedimentary Rocks while Obsidian belongs to Igneous Rocks.Texture of Gritstone is Earthy whereas that of Obsidian is Glassy. Gritstone appears Layered and Foliated and Obsidian appears Shiny. The luster of Gritstone is dull while that of Obsidian is vitreous. Gritstone is available in beige, black, brown, colourless, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Gritstone are an oil and gas reservoir, as a feed additive for livestock, gemstone, metallurgical flux, production of lime, soil conditioner, source of magnesia (mgo), tombstones and that of Obsidian are creating artwork, mirror, used in aquariums.