crystals feldspar felsic floor granit igneous intrusive porphyry quartz rock texture background crystal crystalline grain grained granite Mineral mineralogy nature plagioclase abstract composition conglomerate contrast crack grains grainy gray grey grit gritty igneous-rock layered layers levels light lines mica minerals pitted rock-face rockface rocky rough rugged shape shaped silicate solid stone stonework strata stratum surface surfaces textured textures wallpaper worked calcite green Dirt earth environment metamorphic object science Sed Soil