GENERAL GEOLOGY

Detailed explanation-1: -Correct : Basalt is an example of an extrusive igneous rock.

Detailed explanation-2: -basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium.

Detailed explanation-3: -Basalt is then defined as volcanic rock with a content of 45% to 52% silica and not more than 5% alkali metal oxides.

Detailed explanation-4: -Basalt is classified as a mafic, igneous, volcanic rocks formed by the flow of lava in many different volcanoes. Since basalt is mafic, it contains minerals that are high in iron and magnesium. Since they are a type of igneous rocks, it is not sedimentary.

Detailed explanation-5: -Basalts are dark colored, fine-grained extrusive rock. The mineral grains are so fine that they are impossible to distinguish with the naked eye or even a magnifying glass. They are the most widespread of all the igneous rocks.