ultramafic

[ uhl-truh-maf-ik ]
/ ˌʌl trəˈmæf ɪk /

adjective Geology.

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Origin of ultramafic

First recorded in 1940–45; ultra- + mafic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Scientific definitions for ultramafic

ultramafic
[ ŭl′trə-măfĭk ]

Containing mainly mafic minerals. Used of igneous rocks and often used interchangeably with ultrabasic. Dunite is an ultramafic rock.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.