Igneous Rocks 3

Which of the following CORRECTLY describes about the rock?

• It is a coarse-grained rock.

• It is a mafic rock

• It is a felsic rock.

• It is a fine-grained rock.

• I honestly don't know.

This is a rock observed under a microscope. What mineral do you thinik this is?

• Plagioclase feldspar

• Quartz

• Olivine

• Pyroxene

Why are felsic minerals usually lighter in colour?

• High amount of SiO2

• High amount of MgO & FeO

• High amount of MgO only

• High amount of FeO only

The dotted line represents the composition of Rock A. Which of the following minerals are present in Rock A?

• Ca-rich plagioclase feldspar

• Olivine

• Amphibole

• Quartz

What is the other term for mafic rocks?

• Basaltic rocks

• Basic rocks

• Andesitic rocks

• Silicic rocks

This is a basalt rock. How would you describe the physical characteristics of this rock?

• Fine-grained

• Dark coloured

• Coarse-grained

• Light-coloured

One is granite and the other is gabbro. What is the major difference between the two?

• Their composition

• Their grain sizes

• Their textures

• Their shapes