The silica that comes in little packets designed to dry everything out is silica gel, a form of silicon dioxide, the material found in quartz. Silica is essentially a porous sand that functions as a desiccant, or a drying agent. It can absorb about 40 percent of its weight in moisture. These packets are designed to keep water away from products that shouldn’t get damp, like electronics or dry food. Learn more from Discover Magazine.