Quartz | Common Minerals
Quartz is a common component of silicarich igneous rocks, forming up to 25% of the volume of granites. It also occurs in hydrothermal veins and pegmatites. Because quartz is relatively stable at surface temperatures and pressures, it can be concentrated by weathering processes to be even more abundant in sedimentary rocks than it is in igneous rocks. Quartz sand grains are a .