Identify the minerals present and estimate their relative abundance:
Note patterns like columnar jointing (hexagonal columns) or cooling cracks. The Field Description of Igneous Rocks
Estimate the percentage of dark minerals (Mafic Index). Identify the minerals present and estimate their relative
Note the overall color. Use terms like leucocratic (light-colored/felsic), mesocratic (medium), or melanocratic (dark-colored/mafic). or melanocratic (dark-colored/mafic).