Question

Number the following igneous rock types according to how mafic they are, with 1 being the least mafic (most felsic) and 4 being the most mafic. A. Andesite.B. Basalt.C. Peridotite.D. Rhyolite.

Answer 1

1. Peridotite

2. Basalt

3. Andesite

4. Rhyolite

Explanation:

The igneous rocks all have the same basis when it comes to their formation, but still many variations occur that determine their composition. The variations come from the factors such as the location where they have been formed, the composition of the magma/lava that formed them, the pressure they experienced etc.

This has led to the formation of four different groups of igneous rocks when it comes to their composition. One groups is the ultramafic, and a representative for this group is the peridotite. The mafic group is represented by the basalt. The intermediate group is represented by the andesite, and the felsic group is represented by the rhyolite.

It is relatively easy to distinguish these four groups by their appearance, as some have coarse-grained textures, while the others have fine-grained textures. The coarse-grained textures indicate intrusive rocks, while the fine-grained are indicator of extrusive rocks.