Know all about Siltstone and Icelandite properties here. All properties of rocks are important as they define the type of rock and its application. Siltstone belongs to Sedimentary Rocks while Icelandite belongs to Igneous Rocks.Texture of Siltstone is Clastic whereas that of Icelandite is Aphanitic to Porphyritic. Siltstone appears Rough and Icelandite appears Dull and Soft. The luster of Siltstone is dull while that of Icelandite is vitreous. Siltstone is available in brown, red, reddish brown colors whereas Icelandite is available in bluish - grey, grey, pink, yellow colors. The commercial uses of Siltstone are raw material for the manufacture of mortar, soil conditioner and that of Icelandite are cemetery markers, creating artwork.