This article refers to the material. For other uses, see Glass (disambiguation).Glass is a uniform amorphous solid material, usually produced when the viscous molten material cools very rapidly to below its glass transition temperature, without sufficient time for a regular crystal lattice to form. The most familiar form of glass is the silica-based material used for windows, containers and decorative objects.
In its pure form glass is a transparent, strong, hard-wearing, essentially inert, and biologically inactive material that can be formed with very smooth and impervious surfaces. Glass is, however, brittle and will break into sharp shards. These properties can be modified or changed with the addition of other compounds or heat treatment.
Common glass contains about 70% amorphoussilicon dioxide (SiO2), which is the same chemical compound found in quartz and in its polycrystalline form, sand.