During the Late Bronze Age there was a rapid growth in glassmaking technology in Egypt and Western Asia. However, red-orange glass beads excavated from the Indus Valley Civilization dated before 1700 BC (possibly as early as 1900 BC) predate sustained glass production, which appeared around 1600 BC in Mesopotamia and 1500 BC in Egypt. Įarly glass was rarely transparent and often contained impurities and imperfections, and is technically faience rather than true glass, which did not appear until the 15th century BC. The earliest known glass objects, of the mid-third millennium BC, were beads, perhaps initially created as accidental by-products of metalworking ( slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Archaeological evidence suggests that the first true synthetic glass was made in Lebanon and the coastal north Syria, Mesopotamia or ancient Egypt. Glassmaking dates back at least 6000 years, long before humans had discovered how to smelt iron. Naturally occurring obsidian glass was used by Stone Age societies as it fractures along very sharp edges, making it ideal for cutting tools and weapons. Main article: History of glass Roman cage cup from the 4th century BC Extruded glass fibres have application as optical fibres in communications networks, thermal insulating material when matted as glass wool so as to trap air, or in glass-fibre reinforced plastic ( fibreglass). The refractive, reflective and transmission properties of glass make glass suitable for manufacturing optical lenses, prisms, and optoelectronics materials. Glass can be coloured by adding metal salts or painted and printed with vitreous enamels, leading to its use in stained glass windows and other glass art objects. In its most solid forms, it has also been used for paperweights and marbles. Due to its ease of formability into any shape, glass has been traditionally used for vessels, such as bowls, vases, bottles, jars and drinking glasses. The earliest known glass objects were beads, perhaps created accidentally during metalworking or the production of faience. Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia, Egypt, or Syria. Some objects, such as drinking glasses and eyeglasses, are so commonly made of silicate-based glass that they are simply called by the name of the material.ĭespite being brittle, buried silicate glass will survive for very long periods if not disturbed, and many examples of glass fragments exist from early glassmaking cultures. The term glass, in popular usage, is often used to refer only to this type of material, although silica-free glasses often have desirable properties for applications in modern communications technology. Soda–lime glass, containing around 70% silica, accounts for around 90% of manufactured glass. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. Glass is most often formed by rapid cooling ( quenching) of the molten form some glasses such as volcanic glass are naturally occurring. It has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is a non-crystalline solid that is often transparent, brittle and chemically inert. For other uses, see Glass (disambiguation).
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