Felsic Rocks: Common Minerals and Characteristics

What minerals are commonly found in felsic rocks?

a. Quartz and feldspar
b. Olivine and pyroxene
c. Amphibole and biotite
d. Garnet and magnetite
Final answer:

Answer:

Quartz and feldspar are the primary minerals found in felsic rocks. They give these rocks their light color and high silica and potassium content.

Explanation: The minerals commonly found in felsic rocks are quartz and feldspar. Felsic rocks such as granite or rhyolite are typically high in silica and potassium, and low in iron and magnesium, which contributes to their light color in comparison with mafic and ultramafic rocks. These rocks are also characterized by a high concentration of aluminum and sodium-rich minerals and lesser amounts of biotite.

In addition to quartz and feldspar, these rocks can also sometimes contain muscovite, potassium feldspar, and Na-rich plagioclase. These minerals often give color properties to the rocks they are part of. For instance, potassium feldspar is characterized by its pink, white, or grey color, while biotite is recognized by its black flakes.

Other minerals, such as amphibole (Hornblende) and pyroxene (Augite), are more common in mafic rocks like gabbro or basalt. It's essential to remember that iron and magnesium-bearing minerals typically make up mafic and ultramafic igneous rocks while silica and potassium-rich minerals make up intermediate and felsic igneous rocks.