Thus a system of classification based solely on the minerals present can only be used. We can easily the inadequacy of a mineralogical classification based on minerals present if you look at the classification schemes for volcanic rocks given in introductory geology textbooks. I have yet to see a dacite that contains alkali feldspar. Not really, these are the minerals that should crystallize from a dacite magma, but don't because the crystallization history is interrupted by rapid cooling on the surface. Texture of the Rock .
Rock texture depends to a large extent on cooling history of the magma.
Thus rocks with the same chemical composition and same minerals present could have widely different textures. Color of a rock depends on the minerals present and on their grain size. But color can be misleading when applied to rocks of the same composition but different grain size. For example a granite consists of lots of quartz and feldspar and is generally light colored. But, this does not allow for a very detailed classification scheme.