Answer: the amount of silica minerals in granite
Step-by-step explanation:
Usually, 70-77 percent silica, 11-13 percent alumina, 3-5 percent potassium oxide, 3-5 percent soda, 1 percent lime, 2-3 percent total iron, and less than 1 percent magnesia and titania are the chemical composition of granite. Rhyolite is another kind of volcanic rock with a similar or equivalent chemical composition and mineralogy. Due to high precense of silica the color of granite appears lighter.