Back صخر فوق مافي Arabic Roca ultramàfica Catalan Ultramafická hornina Czech Ultramafisches Gestein German Roca ultramáfica Spanish Arroka ultramafiko Basque سنگ فرامافیک Persian Ultramafinen Finnish Roche ultramafique French Rocha ultramáfica Galician
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are usually composed of greater than 90% mafic minerals (dark colored, high magnesium and iron content). The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks.