Microscopic Structure and Formation of Glass
– Glass is a non-crystalline solid with a high degree of short-range order.
– It lacks long-range periodicity and exhibits all the mechanical properties of a solid.
– Glass can form when a supercooled liquid is rapidly cooled, preventing crystallization.
– The rigidity theory can predict glass-forming ability.
– Glass exists in a structurally metastable state and lacks a first-order phase transition.

Occurrence of Glass in Nature
– Volcanic glass, such as obsidian, is formed from volcanic magma.
– Impactite, like Moldavite and Libyan desert glass, is formed by meteorite impact.
– Vitrification of quartz can occur when lightning strikes sand, forming fulgurites.
– Trinitite is a glassy residue formed from nuclear bomb tests.
– Edeowie glass is proposed to originate from fires, lightning strikes, or asteroid/comet impacts.

History of Glass Production
– Glassmaking dates back at least 6000 years.
– Synthetic glass was first made in Lebanon, Syria, Mesopotamia, or ancient Egypt.
– The earliest known glass objects were beads from the mid-third millennium BC.
– Early glass was rarely transparent and often contained impurities.
– True glass appeared in the 15th century BC.
– The island of Murano in Venice became a center for glassmaking in the 13th century.

Uses and Applications of Glass
– Glass has practical, technological, and decorative uses.
– It is used in window panes, tableware, and optics.
– Silicate glasses based on silica (silicon dioxide) are the most common.
– Glass is used for vessels, paperweights, marbles, and glass art objects.
– It is suitable for manufacturing lenses, prisms, and optical fibers.

Use of Glass in Architecture and Other Applications
– Glass was extensively used in Europe during the Middle Ages, particularly in stained glass windows of churches and cathedrals.
– With the change in architectural style during the Renaissance period, the use of large stained glass windows became less prevalent.
– In the late 19th century, ornamental glass objects became important art mediums during the Art Nouveau period.
– Modern multi-story buildings often have curtain walls made almost entirely of glass.
– Glass is also used as the aperture cover in many solar energy collectors.
– Glass is widely used in optical systems as lenses, windows, mirrors, and prisms.
– The refractive index, dispersion, and transmission of glass depend on its chemical composition and thermal history.
– Glass transparency is due to the absence of grain boundaries that scatter light in polycrystalline materials.
– Glasses can be opaque to certain wavelengths of light, but some types, like heavy-metal fluoride and chalcogenide glasses, are transparent to infrared wavelengths.
– Glass has been widely applied to vehicles for windshields.
– Glass is used for spectacles and lenses, aiding astronomers and having other applications in medicine and science.
– Glass manufacturers have developed chemically strengthened glass for touchscreens in smartphones and tablet computers.
– Pilkington Bros. developed the float glass process in the 1950s, producing high-quality flat sheets of glass.
– Glass can be etched or molded to create art and designs on its surface.
– Glass transparency results from the absence of grain boundaries that scatter light.
– Crystallization can induce semi-opacity in glasses.
– Different colored glasses can be produced by adding metallic oxides that absorb specific wavelengths of light.
– Glass can be modified to have different refractive indices by adding high-density or low-density additives.
– Silicate glasses are generally opaque to infrared wavelengths, while heavy-metal fluoride and chalcogenide glasses are transparent to them.Sources: