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Why is window glass usually made from silicate glass rather than crystalline quartz?
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amorphous solid
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Window glass is typically made from silicate glass rather than crystalline quartz because of the fundamental differences between amorphous solids and crystalline solids.
While quartz is a naturally occurring crystalline form of silica, it possesses a rigid, ordered atomic structure that makes it unsuitable for the mass production of transparent, affordable, and durable windows. In contrast, silicate glass is an amorphous solid prepared by cooling a melt, which allows it to be shaped into large, uniform sheets.12
The primary reasons for this preference include:
- Manufacturing and Cost: Most commercial glass is based on the soda-lime-silica system. By adding ingredients like soda and lime to silica, manufacturers can lower the melting point and improve workability, making the production of windows, containers, and lightbulbs cost-effective.3
- Material Properties: While vitreous silica (fused quartz) is used for specialized applications requiring high thermal shock resistance or ultraviolet transparency, it is more expensive to produce than common soda-lime glass.34
- Structural Nature: Crystalline quartz is a hard, brittle mineral with a fixed, repeating atomic structure. Amorphous silicate glass lacks this long-range order, allowing it to be formed into complex, large-scale geometries without the limitations imposed by the growth of individual crystal grains.5412