Final answer:
Yes, it is true that all of the most common rock-forming minerals in Earth's crust are silicate minerals, which constitute approximately 90% of the crust's composition, exemplified by quartz and found in various rock types.
Step-by-step explanation:
The statement that all of the most common rock-forming minerals in Earth's crust are silicate minerals is true. Silicates, which are minerals that include the silicon-oxygen tetrahedron (SiO4) as their basic structure, indeed make up approximately 90% of the Earth's crust. This is largely due to the abundance of oxygen and silicon, which are the two most abundant elements in the earth's crust.
Quartz is one of the quintessential examples of a silicate mineral and is highly prevalent in the Earth's crust. Rocks such as granite, arkose sandstone, and gneiss display a composition that often includes silicate minerals like K-feldspar, quartz, plagioclase feldspar, and biotite. Furthermore, the modification processes rocks undergo, including their origins as igneous rock and subsequent transformations to sedimentary and then metamorphic rock, typically involve silicate minerals.