What is a defining characteristic of felsic igneous rocks?

Felsic igneous rocks are defined by their light color and lower density compared to other types of igneous rocks. This characteristic is primarily due to their mineral composition, which includes a higher proportion of silica and lighter-colored minerals such as quartz and feldspar. The term "felsic" actually derives from a combination of "feldspar" and "silica."

The lighter coloration results from the presence of these minerals, which reflect more light than darker minerals, giving felsic rocks their distinct appearance. Additionally, because these rocks are rich in silica, they tend to have a lower overall density compared to mafic rocks, which are darker and contain higher amounts of iron and magnesium. This reduced density is an important aspect of how felsic igneous rocks are categorized and identified in geological studies.