A ubiquitous building material, glass is a hard, brittle and transparent solid material that is used in a variety of ways across different industries, from architecture and building to science and technology.
Glass is made by melting together a silicate (e.g. silicon oxide or quartz) and an alkali (soda, lime, etc.). The resulting matter is a non-crystalline structure. The most common kind of glass is silicate glass, which consists mainly of silica or silicon dioxide (SiO2). Silicon dioxide is the chemical makeup of sand, which is why many people say that glass is made from sand—it is a primary component.
Other substances can be added to make different kinds of glass. Boron oxide added to the mixture will make a tougher glass that remains solid at high temperatures, such as the glass used in kitchens and laboratories. Iron alters optical properties of glass and can be found in decorative glass applications. Glass can be colored by adding metallic salts, and can also be painted after manufacturing.
Glass both reflects and refracts light. Cutting and polishing glass in certain ways enhance these qualities and create optical lenses, prisms, fine glassware, and optical fibers for high speed data transmission by light.

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