ultrabasic

[ uhl-truh-bey-sik ]

adjective

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

ultrabasic

/ ˌʌltrəˈbeɪsɪk /

adjective

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

ultrabasic

/ 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.

Word History and Origins

Origin of ultrabasic¹

First recorded in 1890–95; ultra- + basic

Example Sentences

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

From Project Gutenberg