ultrabasic

[ uhl-truh-bey-sik ]

/ ˌʌl trəˈbeɪ sɪk /

adjective

(of rocks) containing iron and magnesium, with little or no silica.

Nearby words

ultra, ultra filtration, ultra vires, ultra-, ultra-distance, ultrabasic, ultracentrifuge, ultraclean, ultraconservative, ultracrepidarian, ultracritical

Also ultramafic.

Origin of ultrabasic

First recorded in 1890–95; ultra- + basic

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ultrabasic

These range from acid to ultrabasic types and include granite, augite-diorite, picrite and serpentine.
Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8|Various

British Dictionary definitions for ultrabasic

ultrabasic

/ (ˌʌltrəˈbeɪsɪk) /

adjective

(of such igneous rocks as peridotite) containing less than 45 per cent silica

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for ultrabasic

ultrabasic

[ ŭl′trə-bā′sĭk ]

Containing magnesium and iron and only a very small amount of silica. Used of igneous rock, and often used interchangeably with ultramafic. Peridotite is an ultrabasic rock.