ultrabasic

American

[uhl-truh-bey-sik] / ˌʌl trəˈbeɪ sɪk /

adjective

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

ultrabasic British

/ 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

ultrabasic Scientific

/ 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.

Etymology

Origin of ultrabasic

First recorded in 1890–95; ultra- + basic

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

These range from acid to ultrabasic types and include granite, augite-diorite, picrite and serpentine.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8 "Dubner" to "Dyeing" by Various

In the form of isolated grains the mineral is a characteristic constituent of ultrabasic igneous rocks, namely the peridotites and the serpentines which have resulted from their alteration.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 3 "Chitral" to "Cincinnati" by Various

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023