Vitreous
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'''Vitreous''' refers to a material in an [[amorphous]], [[glass]]y state (in contrast to a [[crystalline]] state). In such a state, the constituent [[atom]]s do not exhibit the [[long-range order]] that is characteristic of [[crystal]]s. However, they still exhibit short-range order -- the separation of atoms and/or the lengths of [[covalent bond]]s are very close to their typical [[chemical equilibrium|equilibrium]] distances. The creation of a '''vitreous''' material by [[supercooling]] or by addition of additives prior to cooling is called [[vitrification]].
Under certain conditions, vitreous materials may begin to rearrange themselves into [[crystal]]s. This process is referred to as '''devitrification'''. Natural [[volcanic]] glass, [[obsidian]], will de-vitrify or crystallize over extended periods of [[geologic time]]. Devitrification can also occur in glass items that are regularly washed in [[dishwasher]]s due to the chemicals involved in their detergents.<ref>[http://www.newi.ac.uk/buckleyc/materials.htm#Glass Ancient glass] (has a section mentioning devitrification)</ref>
==Other uses==
*When applied to whiteware [[ceramic]]s, vitreous means the material has an extremely low permeability to liquids, often but not always water, when determined by a specified test regime. The microstructure of whiteware [[ceramic]]s frequently contain both [[amorphous]] and crystalline phases.
*A vitreous [[Lustre (mineralogy)|luster]] in [[mineralogy]] refers to a glassy luster or sheen of a mineral surface. The minerals [[quartz]] and [[fluorite]] exhibit a vitreous luster.
*The [[vitreous humour]] (British spelling) or vitreous humor (U.S. spelling) is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates.
==See also==
*[[Amorphous]]
*[[Glass]]
*[[Vitrification]]
==References==
<references/>
{{wiktionary}}
[[Category:Mineralogy]]
[[Category:Amorphous solids]]
[[Category:Glass]]
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