Know all about Gneiss and Tachylite properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Tachylite belongs to Igneous Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Tachylite is Vitreous. Gneiss appears Foliated and Tachylite appears Glassy. The luster of Gneiss is dull while that of Tachylite is resinous. Gneiss is available in black, brown, pink, red, white colors whereas Tachylite is available in black, dark brown colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Tachylite are cemetery markers, creating artwork.