Do Rocks Contain Silica?

Do Rocks Contain Silica? Do rocks contain silica? Most igneous rocks contain between 45 and 70 wt% silica. They range from lower-silica basalt and gabbro to higher-silica rhyolite and granite. Which rock contains the most silica? In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with