Igneous rocks made mostly of the mafic minerals hypersthene, augite, and/or olivine.

Glossary of volcanic terms. - University of Wisconsin Oshkosh. . 2001.

Look at other dictionaries:

  • ultramafic — adjective Date: 1933 ultrabasic …   New Collegiate Dictionary

  • ultramafic — /ul treuh maf ik/, adj. Geol. ultrabasic. [1940 45; ULTRA + MAFIC] * * * …   Universalium

  • ultramafic — adjective Describing igneous rocks that contain magnesium and iron and only a very small amount of silica, such as are found in the Earth’s mantle. Syn: ultrabasic …   Wiktionary

  • ultramafic — adj. with high ferro magnesium content; extremely basic and low in silica and rich in iron and magnesium minerals …   English contemporary dictionary

  • ultramafic — [ˌʌltrə mafɪk] adjective Geology relating to or denoting igneous rocks composed chiefly of mafic minerals …   English new terms dictionary

  • ultramafic — ul·tra·mafic …   English syllables

  • ultramafic — |əltrə+ adjective Etymology: ultra + mafic : ultrabasic …   Useful english dictionary

  • Ultramafic rock — Ultramafic (also referred to as ultrabasic) rocks are igneous and meta igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark… …   Wikipedia

  • Ultramafic to mafic layered intrusions — are found in typically ancient cratons and are rare but worldwide in distribution. The intrusive complexes exhibit evidence of fractional crystallization and crystal segregation by settling or floating of minerals from a melt. Ideally the… …   Wikipedia

  • ultramafic rock — /ʌltrəˌmæfɪk ˈrɒk/ (say ultruh.mafik rok) noun → ultrabasic rock …   Australian English dictionary