Wikipedia:Today's featured article/September 17, 2004

In its pure form, glass is a transparent, relatively strong, hard-wearing, essentially inert, and biologically inactive material which can be formed with very smooth and impervious surfaces. These desirable properties lead to its very many uses. Glass is, however, brittle and will break into sharp shards. These properties can be modified, or even changed entirely, with the addition of other compounds. Glasses are uniform amorphous solid materials, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. Glasses can be made from many materials, although only a few varieties are in common use. Common glass is mostly amorphous silicon dioxide, which is the same chemical compound as quartz, or, in its polycrystalline form, sand. (more...)

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