According to the IUGS classification of igneous rocks, harzburgite is characterized by a composition dominated by olivine and orthopyroxene. The given rock composition, with 55% olivine, 40% orthopyroxene, and 5% plagioclase, fits the definition of harzburgite.
Group I | Group II |
P. Sillimanite | 1. First order |
Q. Quartz | 2. Second order |
R. Muscovite | 3. Greater than third order |
S. Calcite | 4. Third order variegated |