Know all about Greywacke and Nephelinite properties here. All properties of rocks are important as they define the type of rock and its application. Greywacke belongs to Sedimentary Rocks while Nephelinite belongs to Igneous Rocks.Texture of Greywacke is Clastic whereas that of Nephelinite is Aphanitic. Greywacke appears Dull and Nephelinite appears Skeletal. The luster of Greywacke is dull while that of Nephelinite is vitreous to metallic. Greywacke and Nephelinite are available in beige, black, brown, colourless, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow colors. The commercial uses of Greywacke are as armour rock for sea walls, petroleum reservoirs, sea defence, tombstones and that of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo).