|Section2= |Section3= |Section4= |Section5= }} The chemical compound silicon dioxide, also known as silica or silox (from the Latin "silex"), is an oxide of silicon, chemical formula, and has been known for its hardness since the 9th century. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms. It is a principal component of most types of glass and substances such as concrete. Manufactured forms Silica is manufactured in several forms including: gl… (More on Silica)