Silicas are compounds that have a molecular structure consisting of silicon and oxygen. There are various types of silicas found in nature, each with unique properties making them useful in different applications. Some common synonyms for silicas include silicon dioxide, silicate, quartz, and silica fume. Silicon dioxide is the most common form of silica and is used in the production of glass, ceramics, and electronics. Silicate, on the other hand, is found in rocks and minerals such as clay and feldspar. Quartz is a transparent crystalline form of silica, often used in jewelry and watches. Silica fume is a fine powder that results from silicon metal production and is often used in concrete mixes to improve strength and durability.