Ultramafic rocks are a type of igneous rock that contains a high percentage of magnesium and iron, with low silica content. They are typically dark in color and dense, primarily composed of minerals like olivine and pyroxene. These rocks are often found in the Earth's mantle and can be brought to the surface through volcanic activity. Common examples of ultramafic rocks include peridotite and dunite. Due to their unique mineral composition, ultramafic rocks play a significant role in understanding the Earth's geology and the processes that shape our planet. They are also important in the study of mantle dynamics and the formation of oceanic crust.