Silica sand is commonly used in building materials such as mortar and concrete.
Silica Gel is a form of silicon dioxide used to remove moisture from liquids and gasses. It's benefits were largely misunderstood following it's discovery in 1640, but it was successfully used in gas masks in WWI, proving its value.
Silica is commonly used in the manufacture of ceramics, being a major ingredient in refractories and white wares. It is added in the form of quartz sand or sandstone to be a filler to help a peice maintain its shape during firing.