Question

Which silicate minerals are the main component of most of Earth's rocks?

Answer 1

Feldspar.

Explanation:

The two most abundant components are feldspar and quartz, whereas feldspar makes up around 41% of the Earth's continental crust by weight.

For your reference:
https://en.wikipedia.org/wiki/Feldspar
Geology: Why do feldspars make up such a large percent (60%) of the Earth's crust?
https://www.ck12.org/earth-science/Mineral-Groups/lesson/Mineral-Groups-HS-ES/