Silicon dioxide is a hard substance, not soluble in water and a poor conductor of electricity. The sand on beaches is made up of silicon dioxide or silica. Silicon dioxide is also the main component found in quartz and sandstone.
Although sand and quartz may have the same chemical formula, the difference between the two is that quartz forms into a large crystal shape and sand grains are small. Likewise, sand may consists of mainly silica, but it also contains some other mineral substances. Both these forms of silicon dioxide are found in nature in abundant quantities.Learn more about States of Matter