The black type is aphanitic as opposed to the grey variety and a similar chemically composed rock.
The black type is aphanitic as opposed to the grey variety and a similar chemically composed rock. The alkali type usually contains pyroxene or titaniferous augite, while the tholeiitic type can have pyroxenes, augite, or pigeonite. With high iron and magnesium, its lava covers much ground and has a low viscosity, partly because of the low silica content common in mafic rocks. For ten points identify this extrusive rock found extensively in the ocean floor.
The black type is aphanitic as opposed to the grey variety and a similar chemically composed rock.
{basalt}