Glass

Glass in the common sense refers to a hard, brittle, transparent solid, such as used for windows, many bottles, or eyewear, including soda-lime glass, acrylic glass, sugar glass, isinglass (Muscovy-glass), or aluminium oxynitride. more...

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In the technical sense, glass is an inorganic product of fusion which has been cooled to a rigid condition without crystallizing. Most glasses contain silica as their main component and glass former.

In the scientific sense the term glass is often extended to all amorphous solids (and melts that easily form amorphous solids), including plastics, resins, or other silica-free amorphous solids. In addition, besides traditional melting techniques, any other means of preparation are considered, such as ion implantation, and the sol-gel method. However, glass science commonly includes only inorganic amorphous solids, while plastics and similar organics are covered by polymer science, biology and further scientific disciplines.

The optical and physical properties of glass make it suitable for applications such as flat glass, container glass, optics and optoelectronics material, laboratory equipment, thermal insulator (glass wool), reinforcement fiber (glass-reinforced plastic, glass fiber reinforced concrete), and art.

General properties, uses, occurrence

Ordinary glass is prevalent due to its transparency to visible light. This transparency is due to an absence of electronic transition states in the range of visible light. The homogeneity of the glass on length scales greater than the wavelength of visible light also contributes to its transparency as heterogeneities would cause light to be scattered, breaking up any coherent image transmission. Many household objects are made of glass. Drinking glasses, bowls and bottles are often made of glass, as are light bulbs, mirrors, aquaria, cathode ray tubes, computer flat panel displays, and windows.

In research laboratories, flasks, test tubes, and other laboratory equipment are often made of borosilicate glass for its low coefficient of thermal expansion, giving greater resistance to thermal shock and greater accuracy in measurements. For high-temperature applications, quartz glass is used, although it is very difficult to work. Most laboratory glassware is mass-produced, but large laboratories also keep a glassblower on staff for preparing custom made glass equipment.

Sometimes, glass is created naturally from volcanic lava, lightning strikes, or meteorite impacts (e.g., Lechatelierite, Fulgurite, Darwin Glass, Volcanic Glass). If the lava is felsic this glass is called obsidian, and is usually black with impurities. Obsidian is a raw material for flintknappers, who have used it to make extremely sharp glass knives since the stone age.

Read more at Wikipedia.org