Igneous Rocks

Igneous rock identification uses combination of texture and mineral composition groups. Textures include phaneritic (coarse), aphanitic (fine), glassy, vesicular (porous), pyroclastic (volcanic granular), and porphyritic (fine and coarse). Mineral content groups include felsic (quartz and orthoclase), intermediate (Na feldspars and amphiboles), mafic (Ca plagioclase and pyroxene), and ultramafic (olivine and pyroxene).