Silica exists in the free state as crystalline or amorphous, and in the combined state as silicates. The main crystalline varieties of silica are quartz, cristobalite and tridymite. In its natural state, crystalline silica (and in particular quartz) is present in many rocks (sandstone, granite, sand, etc.).
As a result, crystalline silica is present in many products such as concretes, mortars, facade plasters, ceramic and porcelain industries, brick and tile industries, construction and public works, etc.
