Ultramafic refers to a type of igneous rock that is composed primarily of magnesium and iron-rich minerals. These rocks typically contain very low amounts of silica, making them dense and dark in color. Common examples of ultramafic rocks include peridotite and dunite, which are often found in the Earth's mantle. Ultramafic rocks play a significant role in geology and are important for understanding the Earth's composition. They can also be associated with valuable mineral deposits, such as chromite and nickel, which are extracted for various industrial uses.