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