Know all about Siltstone and Nephelinite properties here. All properties of rocks are important as they define the type of rock and its application. Siltstone belongs to Sedimentary Rocks while Nephelinite belongs to Igneous Rocks.Texture of Siltstone is Clastic whereas that of Nephelinite is Aphanitic. Siltstone appears Rough and Nephelinite appears Skeletal. The luster of Siltstone is dull while that of Nephelinite is vitreous to metallic. Siltstone is available in brown, red, reddish brown colors whereas Nephelinite is available in black, brown, colourless, green, grey, white colors. The commercial uses of Siltstone are raw material for the manufacture of mortar, soil conditioner and that of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo).