Question

Which of the following statements about basalt is false?

1. basalt is the dominant rock type of the upper oceanic crust
2. pyroxene and plagioclase feldspar are major mineral constituents of basalt
3. basalt may have pahoehoe texture
4. basalt generally forms from magma extruded at or near the Earth's surface
5. basalt has felsic composition

Answer 1

The false statement about basalt is that it has a felsic composition; in reality, basalt is mafic and rich in magnesium and iron.

Step-by-step explanation:

The question asks which statement about basalt is false. Basalt is indeed the dominant rock type of the upper oceanic crust and it consists of major mineral constituents such as pyroxene and plagioclase feldspar. Having a pahoehoe texture and forming from magma extruded at or near the Earth's surface are also true characteristics of basalt.

However, basalt does not have a felsic composition; it is not made of the same light-colored minerals as granite or rhyolite. Basalt is known for its mafic composition, which means it is rich in magnesium and iron and has a darker color.