ultrabasic

American  

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

adjective

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

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ultrabasic British  

/ ˌʌltrəˈbeɪsɪk /

adjective

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

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ultrabasic Scientific  

/ ŭl′trə-bā′sĭk /

1. 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.

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Etymology

Origin of ultrabasic

First recorded in 1890–95; ultra- + basic

Example Sentences

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

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