An igneous rock that consists of ferromagnesian minerals and possesses no free quartz, and with less than 45% silica.
Describing an igneous rock containing magnesium and iron with a very low percentage of silica, less than 45%.
Igneous rock containing less than 45 per cent silica.
igneous rock with very low silica content
plutonic or volcanic rock having a silica content (SiO2) less than 45 %.
extremely rich in base-forming elements and poor in silica. [AHDOS