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A glass is an amorphous solid completely lacking long range periodic atomic structure that exhibits a region of glass transformation.This broad definition means that any material be it organic, inorganic, metallic, etc. in nature may form a glass if it exhibits glass transformation behavior.
Ash-flow tuffs typically consist of countless microscopic shards of volcanic glass. [3] Basalt, which is low in silica, forms glass only with difficulty, so that basalt tephra almost always contains at least some crystalline material (quench crystals). [2] The glass transition temperature of basalt is about 700 °C (1,292 °F). [4]
Because it is often transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware, and optics. Some common objects made of glass are named after the material, e.g., a "glass" for drinking, "glasses" for vision correction, and a "magnifying glass".
The overwhelming consensus of Earth and planetary scientists is that tektites consist of terrestrial debris that was ejected during the formation of an impact crater. During the extreme conditions created by a hypervelocity meteorite impact, near-surface terrestrial sediments and rocks were either melted, vaporized, or some combination of these ...
In physical chemistry and engineering, passivation is coating a material so that it becomes "passive", that is, less readily affected or corroded by the environment. . Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build by spontaneous oxidation
Libyan desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, [1] found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of square kilometers. Like obsidian, it was knapped and used to make tools during the Pleistocene. [2]
Optical glass refers to a quality of glass suitable for the manufacture of optical systems such as optical lenses, prisms or mirrors.Unlike window glass or crystal, whose formula is adapted to the desired aesthetic effect, optical glass contains additives designed to modify certain optical or mechanical properties of the glass: refractive index, dispersion, transmittance, thermal expansion and ...
Other materials, such as many polymers, lack a well defined crystalline state and easily form glasses, even upon very slow cooling or compression. The tendency for a material to form a glass while quenched is called glass forming ability. This ability depends on the composition of the material and can be predicted by the rigidity theory. [12]