Silica (noun)

1. A compound of silicon and oxygen, SiO2, found in various forms such as quartz, sand, and flint.
2. A white or colorless crystalline substance that is the main component of most types of sand and of many rocks.

Origin:

From new latin silica, from latin silex ("flint").

Examples:

1. Silica is used to make glass and ceramics.
2. Silica is the most common mineral in the Earth's crust.
3. The silica in the sand will scratch the car's paint.
4. Silica gel is used to absorb moisture.
5. Silica is used to improve the strength and durability of concrete.