Know all about Obsidian and Alkali Feldspar Granite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Alkali Feldspar Granite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Alkali Feldspar Granite is Phaneritic. Obsidian appears Shiny and Alkali Feldspar Granite appears Veined or Pebbled. The luster of Obsidian is vitreous while that of Alkali Feldspar Granite is dull to grainy with sporadic parts pearly and vitreous. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Alkali Feldspar Granite is available in black, grey, orange, pink, white colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Alkali Feldspar Granite are curling, gemstone, laboratory bench tops, tombstones.