Glass

Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle and optically transparent.

The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica (SiO2) plus sodium oxide Na2O from soda ash, lime CaO, and several minor additives. Often, the term glass is used in a restricted sense to refer to this specific use.

In science, however, the term glass is usually defined in a much wider sense, including every solid that possesses a non-crystalline (i.e., amorphous) structure and that exhibits a glass transition when heated towards the liquid state. In this wider sense, glasses can be made of quite different classes of materials: metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications (bottles, eyewear) polymer glasses (acrylic glass, polycarbonate, polyethylene terephthalate) are a lighter alternative to traditional silica glasses.

Read more about Glass:  Silicate Glass, Structure, Glass Versus Supercooled Liquid, Glass Art

Famous quotes containing the word glass:

    Our ideal ... must be a language as clear as glass—the person looking out of the window knows there is glass there, but he is not concerned with it; what concerns him is what comes through from the other side.
    Elizabeth Bowen (1899–1973)

    People who, out of an inborn moderation, leave every glass standing only half-emptied refuse to admit that everything in the world has its sediments and dregs.
    Friedrich Nietzsche (1844–1900)