Earth Science Laboratory


Your instructor will furnish you with a number of specimens of igneous rocks. You may be given more than one example of a specific rock. Use the information given in the laboratory lecture as well as the textbook references to help you identify these specimens. It will help if you first record the data asked for in the following table to each specimen before attempting to assign a name. Use a microscope or hand lens to aid in identifying the minerals present.
light/ dark / intermediate coarse/ fine/ porphyritic K-feldspar/
plagioclase feldspar
quartz, biotite, muscovite, 
biotite, augite, olivine, etc.
phaneritic/ aphanitic/ porphyritic volcanic/
No. Color Grain Size Chief Feldspar Other Minerals Textural Features Classification Rock Name