Know all about Siltstone and Porphyry properties here. All properties of rocks are important as they define the type of rock and its application. Siltstone belongs to Sedimentary Rocks while Porphyry belongs to Igneous Rocks.Texture of Siltstone is Clastic whereas that of Porphyry is Porphyritic. Siltstone appears Rough and Porphyry appears Dull. The luster of Siltstone and Porphyry is dull. Siltstone is available in brown, red, reddish brown colors whereas Porphyry is available in black, brown, colourless, green, grey, red, rust, white colors. The commercial uses of Siltstone are raw material for the manufacture of mortar, soil conditioner and that of Porphyry are creating artwork, gemstone, jewelry.