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Glass is a non-
crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...
, often
transparent Transparency, transparence or transparent most often refer to transparency and translucency, the physical property of allowing the transmission of light through a material. They may also refer to: Literal uses * Transparency (photography), a sti ...
amorphous solid In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science t ...
, that has widespread practical, technological, and decorative use in, for example,
window A window is an opening in a wall A wall is a structure and a surface that defines an area; carries a load; provides security Security is freedom from, or resilience against, potential Potential generally refers to a currently unrealize ...

window
panes,
tableware upright=1.3, Table laid for six at the Royal Castle, Warsaw, (18th–19th century fashion) Tableware is any dish or dishware used for setting a table, serving food, and dining. It includes cutlery, List of glassware, glassware, serving dishes, ...

tableware
, and
optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

optics
. Glass is most often formed by rapid cooling (
quenching 250px, Coke being pushed into a quenching car, Hanna furnaces of the Great Lakes Steel Corporation, Detroit, Michigan, November 1942 In materials science The Interdisciplinarity, interdisciplinary field of materials science, also commonly terme ...

quenching
) of the
molten Melting, or fusion, is a physical process that results in the phase transition In chemistry, thermodynamics, and many other related fields, phase transitions (or phase changes) are the Physical process, physical processes of transition betw ...

molten
form; some glasses such as
volcanic glass Volcanic glass is the amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nat ...
are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound
silica Silicon dioxide, also known as silica, is an oxide An oxide () is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any su ...
(silicon dioxide, or
quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

quartz
), the primary constituent of
sand Sand is a granular material composed of finely divided rock (geology), rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer ...

sand
.
Soda-lime glass Soda lime is a mixture of NaOH & CaO chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent el ...
, containing around 70% silica, accounts for around 90% of manufactured glass. 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. Some objects, such as drinking glasses and
eyeglasses Glasses, also known as eyeglasses or spectacles, are vision eyewear, consisting of glass or hard plastic lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known ...

eyeglasses
, are so commonly made of silicate-based glass that they are simply called by the name of the material. Although brittle, buried silicate glass will survive for very long periods if not disturbed, and many examples of glass fragments exist from early glass-making cultures. Archaeological evidence suggests glass-making dates back to at least 3,600 BC in
Mesopotamia Mesopotamia ( grc, Μεσοποταμία ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in th ...

Mesopotamia
,
Egypt Egypt ( ar, مِصر, Miṣr), officially the Arab Republic of Egypt, is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses. Generally identi ...

Egypt
, or
Syria Syria ( ar, سُورِيَا or ar, سُورِيَة, ''Sūriyā''), officially the Syrian Arab Republic ( ar, ٱلْجُمْهُورِيَّةُ ٱلْعَرَبِيَّةُ ٱلسُّورِيَّةُ, al-Jumhūrīyah al-ʻArabīyah as-S ...

Syria
. The earliest known glass objects were
beads A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood or pearl and with a small hole for threading or stringing. Beads range in size from under to ...

beads
, perhaps created accidentally during
metalworking Metalworking is the process of shaping and reshaping metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearan ...
or the production of
faience , Italy, which gave its name to the type Faience or faïence (; ) is the general English language English is a West Germanic language of the Indo-European language family, originally spoken by the inhabitants of early medieval England. It ...
. Due to its ease of
formabilityFormability is the ability of a given metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts E ...
into any shape, glass has been traditionally used for vessels, such as
bowls Bowls, or lawn bowls, is a sport Sport pertains to any form of Competition, competitive physical activity or game that aims to use, maintain or improve physical ability and skills while providing enjoyment to participants and, in some ca ...
,
vase A vase ( or ) is an open container. It can be made from a number of materials, such as ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant Corrosion is a natural process that converts a refined met ...

vase
s,
bottle A bottle is a narrow-necked container made of an impermeable material (clay, glass, plastic, aluminium etc.) in various shapes and sizes to store and transport liquids (water, milk, beer, wine, ink, cooking oil, medicine, soft drinks, shampoo ...

bottle
s, jars and drinking glasses. In its most solid forms, it has also been used for paperweights and
marbles A marble is a small spherical object often made from glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window ...

marbles
. Glass can be coloured by adding metal salts or painted and printed as
enamelled glass Enamelled glass or painted glass is glass which has been decorated with vitreous enamel (powdered glass, usually mixed with a binder) and then fired to glass fusing, fuse the glasses. It can produce brilliant and long-lasting colours, and be tr ...
. The
refractive In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throu ...

refractive
,
reflective Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light Light or visible ligh ...
and
transmission Transmission may refer to: Science and technology * Power transmissionPower transmission is the movement of energy from its place of generation to a location where it is applied to perform useful Mechanical work, work. Power (physics), Power is d ...

transmission
properties of glass make glass suitable for manufacturing
optical lenses
optical lenses
,
prism A prism An optical prism is a transparent optics, optical element with flat, polished surfaces that refraction, refract light. At least one surface must be angled—elements with two parallel surfaces are not prisms. The traditional geometrical ...

prism
s, and
optoelectronics Opto-electronics (or optronics) is the study and application of electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of elec ...
materials. Extruded glass fibres have application as
optical fibres An optical fiber (or fibre in British English British English (BrE) is the standard dialect of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, ea ...

optical fibres
in communications networks, thermal insulating material when matted as
glass wool Glass wool is an Thermal insulation, insulating material made from glass fiber, fibres of glass arranged using a Binder (material), binder into a texture similar to wool. The process traps many small pockets of air between the glass, and these sm ...
so as to trap air, or in
glass-fibre Fiberglass (American English), or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened i ...
reinforced plastic (
fibreglass Fiberglass (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English ...
).


Microscopic structure

The standard definition of a ''glass'' (or vitreous solid) is a solid formed by rapid melt
quenching 250px, Coke being pushed into a quenching car, Hanna furnaces of the Great Lakes Steel Corporation, Detroit, Michigan, November 1942 In materials science The Interdisciplinarity, interdisciplinary field of materials science, also commonly terme ...

quenching
. However, the term "glass" is often defined in a broader sense, to describe any non-crystalline (
amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science th ...
) solid that exhibits a
glass transition The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη ...
when heated towards the liquid state. Glass is an
amorphous solid In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science t ...
. Although the atomic-scale structure of glass shares characteristics of the structure of a
supercooled liquid Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) und ...
, glass exhibits all the mechanical properties of a solid. As in other
amorphous solid In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science t ...
s, the atomic structure of a glass lacks the long-range periodicity observed in
crystalline solids A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...

crystalline solids
. Due to
chemical bonding A chemical bond is a lasting attraction between atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday o ...
constraints, glasses do possess a high degree of short-range order with respect to local atomic
polyhedra In geometry Geometry (from the grc, γεωμετρία; ' "earth", ' "measurement") is, with , one of the oldest branches of . It is concerned with properties of space that are related with distance, shape, size, and relative position o ...

polyhedra
. The notion that glass flows to an appreciable extent over extended periods of time is not supported by empirical research or theoretical analysis (see viscosity in solids). Laboratory measurements of room temperature glass flow do show a motion consistent with a material viscosity on the order of 1017–1018 Pa s.


Formation from a supercooled liquid

For melt quenching, if the cooling is sufficiently rapid (relative to the characteristic
crystallization Crystallization or crystallisation is the process by which a solid Solid is one of the four fundamental states of matter 4 (four) is a number A number is a mathematical object A mathematical object is an abstract concept arising ...

crystallization
time) then crystallization is prevented and instead the disordered atomic configuration of the
supercooled Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isoc ...
liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, a glass exists in a structurally
metastable In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's ground state, state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. I ...
state with respect to its
crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...
form, although in certain circumstances, for example in
atactic Tacticity (from Greek τακτικός ''taktikos'' "of or relating to arrangement or order") is the relative stereochemistry s. Stereochemistry focuses on stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomer ...
polymers, there is no crystalline analogue of the amorphous phase. Glass is sometimes considered to be a liquid due to its lack of a first-order
phase transition In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...
where certain
thermodynamic Thermodynamics is a branch of physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related ent ...

thermodynamic
variables such as
volume Volume is a scalar quantity expressing the amount Quantity or amount is a property that can exist as a multitude Multitude is a term for a group of people who cannot be classed under any other distinct category, except for their shared fact ...

volume
,
entropy Entropy is a scientific concept as well as a measurable physical property that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynamic ...

entropy
and
enthalpy Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant p ...

enthalpy
are discontinuous through the glass transition range. The
glass transition The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη ...
may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and
heat capacity Heat capacity or thermal capacity is a physical property A physical property is any property Property is a system of rights that gives people legal control of valuable things, and also refers to the valuable things themselves. Depending on t ...
are discontinuous, however this is incorrect. The equilibrium theory of phase transformations do not hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids. Furthermore, it does not describe the temperature dependence of Tg upon heating rate, as found in differential scanning calorimetry.


Occurrence in nature

Glass can form naturally from volcanic magma.
Obsidian Obsidian (; ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter element ...

Obsidian
is a common volcanic glass with high silica (SiO2) content formed when felsic lava extruded from a volcano cools rapidly.
Impactite Impactite is rock created or modified by one or more impacts of a meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the at ...
is a form of glass formed by the impact of a
meteorite A meteorite is a solid piece of debris from an object, such as a comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces ...
, where
Moldavite Moldavite ( cs, Vltavín) is a forest green, olive green or blue greenish Lustre (mineralogy)#Vitreous lustre, vitreous silica projectile Rock (geology), rock formed by a meteorite impact probably in southern Germany (Nördlinger Ries Crater) that ...

Moldavite
(found in central and eastern Europe), and
Libyan desert glass Image:Libyan Desert Glass.jpg, Libyan desert glass Libyan Desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the Libyan Desert, deserts of eastern Libya and Western Desert ( ...
(found in areas in the eastern
Sahara The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the African continent Africa is the world's second-largest and second-most populous continent A continent is any of several large landma ...

Sahara
, the deserts of eastern Libya and western Egypt) are notable examples.
Vitrification Vitrification (from Latin language, Latin ''vitreum'', "glass" via French language, French ''vitrifier'') is the transformation of a substance into a glass, that is to say, a non-Crystallinity, crystalline amorphous solid. Glasses differ from liqu ...

Vitrification
of
quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

quartz
can also occur when
lightning Lightning is a naturally occurring electrostatic discharge Electrostatic discharge (ESD) is the sudden flow of electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan ...

lightning
strikes
sand Sand is a granular material composed of finely divided rock (geology), rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer ...

sand
, forming hollow, branching rootlike structures called
fulgurite Fulgurites (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of t ...
s.
Trinitite Levels of radioactivity in the trinity glass at the time of explosion from two different samples as measured by gamma spectroscopy on lumps of the glass Trinitite, also known as atomsite or Alamogordo glass, is the glass Glass is a non- cry ...

Trinitite
is a glassy residue formed from the desert floor sand at the
Trinity The Christian Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus in Christianity, Jesus Christ. The words ''Christ (title), Christ'' and ''Christian ...
nuclear bomb test site.
Edeowie glass Edeowie glass is a natural glass, or lechatelierite, found in the Australian state of South Australia. It is slag-like, Opacity (optics), opaque material found as Vesicular texture, vesicular free forms or sheet-like/ropy masses. It is located thro ...
, found in
South Australia South Australia (abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Austral ...

South Australia
, is proposed to originate from
Pleistocene The Pleistocene ( , often referred to as the ''Ice Age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated glaciations. Before a change finally ...
grassland fires,
lightning Lightning is a naturally occurring electrostatic discharge Electrostatic discharge (ESD) is the sudden flow of electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan ...

lightning
strikes, or by one or several
asteroids An asteroid is a minor planet A minor planet is an astronomical object in direct orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet around a star or a ...

asteroids
or
comets A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena a ...

comets
. File:Lipari-Obsidienne (5).jpg, A piece of volcanic
obsidian Obsidian (; ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter element ...

obsidian
glass File:Moldavite Besednice.jpg,
Moldavite Moldavite ( cs, Vltavín) is a forest green, olive green or blue greenish Lustre (mineralogy)#Vitreous lustre, vitreous silica projectile Rock (geology), rock formed by a meteorite impact probably in southern Germany (Nördlinger Ries Crater) that ...

Moldavite
, a natural glass formed by
meteorite A meteorite is a solid piece of debris from an object, such as a comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces ...
impact, from ,
Bohemia Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region Historical regions (or historical areas) are geographical Geography (from Greek Greek may refer to: Greece Anything of, from, ...
File:Fulgurites-algeria.jpg, Tube File:Trinitite from Trinity Site.jpg,
Trinitite Levels of radioactivity in the trinity glass at the time of explosion from two different samples as measured by gamma spectroscopy on lumps of the glass Trinitite, also known as atomsite or Alamogordo glass, is the glass Glass is a non- cry ...

Trinitite
, a glass made by the Trinity nuclear-weapon test File:Libyan Desert Glass.jpg,
Libyan desert glass Image:Libyan Desert Glass.jpg, Libyan desert glass Libyan Desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the Libyan Desert, deserts of eastern Libya and Western Desert ( ...


History

Naturally occurring
obsidian Obsidian (; ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter element ...

obsidian
glass was used by
Stone Age The Stone Age was a broad prehistoric Prehistory, also known as pre-literary history, is the period of human history Human history, also known as world history, is the description of humanity's past. It is informed by archaeology ...

Stone Age
societies as it fractures along very sharp edges, making it ideal for cutting tools and weapons. Glassmaking dates back at least 6000 years, long before humans had discovered how to
smelt Smelt may refer to: * Smelting, chemical process *The common name of various fish ** Smelt (fish), a family of small fish, Osmeridae ** Australian smelt in the family Retropinnidae and species ''Retropinna semoni'' ** Big-scale sand smelt ''Atherin ...
iron. Archaeological evidence suggests that the first true synthetic glass was made in
Lebanon Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon or the Lebanese Republic, is a country in Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion A subregion is a part ...

Lebanon
and the coastal north
Syria Syria ( ar, سُورِيَا or ar, سُورِيَة, ''Sūriyā''), officially the Syrian Arab Republic ( ar, ٱلْجُمْهُورِيَّةُ ٱلْعَرَبِيَّةُ ٱلسُّورِيَّةُ, al-Jumhūrīyah al-ʻArabīyah as-S ...

Syria
,
Mesopotamia Mesopotamia ( grc, Μεσοποταμία ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in th ...

Mesopotamia
or
ancient Egypt Ancient Egypt was a civilization  A civilization (or civilisation) is a that is characterized by , , a form of government, and systems of communication (such as ). Civilizations are intimately associated with additional char ...

ancient Egypt
. The earliest known glass objects, of the mid-third millennium BC, were
beads A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood or pearl and with a small hole for threading or stringing. Beads range in size from under to ...
, perhaps initially created as accidental by-products of
metalworking Metalworking is the process of shaping and reshaping metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearan ...
(
slag Slag is a by-product of smelting Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, ...

slag
s) or during the production of
faience , Italy, which gave its name to the type Faience or faïence (; ) is the general English language English is a West Germanic language of the Indo-European language family, originally spoken by the inhabitants of early medieval England. It ...
, a pre-glass vitreous material made by a process similar to glazing. Early 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. However, red-orange glass beads excavated from the
Indus Valley Civilization The Indus Valley Civilisation (IVC), also known as the Indus Civilisation, was a Bronze Age The Bronze Age is a prehistoric that was characterized by the use of , in some areas , and other early features of urban . The Bronze Age is ...
dated before 1700 BC (possibly as early as 1900 BC) predate sustained glass production, which appeared around 1600 in Mesopotamia and 1500 in Egypt. During the
Late Bronze Age The Bronze Age is a prehistoric Periodization, period that was characterized by the use of bronze, in some areas proto-writing, and other early features of urban civilization. The Bronze Age is the second principal period of the Three-age sys ...
there was a rapid growth in
glassmaking Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass. Glass containe ...

glassmaking
technology in
Egypt Egypt ( ar, مِصر, Miṣr), officially the Arab Republic of Egypt, is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses. Generally identi ...

Egypt
and
Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Anat ...

Western Asia
. Archaeological finds from this period include coloured glass
ingots An ingot is a piece of relatively pure material, usually metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appe ...
, vessels, and beads. Much early glass production relied on grinding techniques borrowed from , such as grinding and carving glass in a cold state. The term ''glass'' developed in the late
Roman Empire The Roman Empire ( la, Imperium Rōmānum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican Republican can refer to: Political ideology * An advocate of a republic, a type of governme ...

Roman Empire
. It was in the
Roman glass Roman glass objects have been recovered across the Roman Empire in domestic, industrial and funerary contexts. Glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, ...
making centre at
Trier Trier ( , ; lb, Tréier ), formerly known in English as Trèves ( ;) and Triers (see also Names of Trier in different languages, names in other languages), is a city on the banks of the Moselle (river), Moselle in Germany. It lies in a valley b ...

Trier
(located in current-day Germany), that the late-Latin term ''glesum'' originated, probably from a
Germanic Germanic may refer to: * Germanic peoples, an ethno-linguistic group identified by their use of the Germanic languages ** List of ancient Germanic peoples and tribes * Germanic languages :* Proto-Germanic language, a reconstructed proto-language of ...

Germanic
word for a
transparent Transparency, transparence or transparent most often refer to transparency and translucency, the physical property of allowing the transmission of light through a material. They may also refer to: Literal uses * Transparency (photography), a sti ...
,
lustrous Lustre (British English British English (BrE) is the standard dialect of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which ...
substance. Glass objects have been recovered across the Roman Empire in domestic,
funerary A funeral is a ceremony A ceremony (, ) is a unified ritual A ritual is a sequence of activities involving gesture A gesture is a form of non-verbal communication or non-vocal communication Communication (from Latin ''communicare' ...
, and industrial contexts. Examples of
Roman glass Roman glass objects have been recovered across the Roman Empire in domestic, industrial and funerary contexts. Glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, ...
have been found outside of the former
Roman Empire The Roman Empire ( la, Imperium Rōmānum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican Republican can refer to: Political ideology * An advocate of a republic, a type of governme ...

Roman Empire
in
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
, the
Baltics The Baltic states ( et, Balti riigid, Baltimaad; lv, Baltijas valstis; lt, Baltijos valstybės), also known as the Baltic countries, Baltic republics, Baltic nations, or simply the Baltics, is a geopolitical term, typically used to group the ...
, the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233 The international standard An international standard is a technical standard A technical standard is an established norm (social), norm or requirement for a repeatable technical task whi ...

Middle East
, and
India India, officially the Republic of India (Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, ...

India
. The Romans perfected
cameo glass 250px, The Portland Vase, about 5–25 AD Cameo glass is a luxury form of glass art Glass art refers to individual works of art that are substantially or wholly made of glass. It ranges in size from monumental works and installation pieces to wall ...
, produced by
etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in Intaglio (printmaking), intaglio (incised) in the metal. In modern manufacturing, other chemicals may ...
and carving through fused layers of different colours to produce a design in relief on the glass object. In post-classical West Africa,
Benin Benin ( , ; french: Bénin ), officially the Republic of Benin (french: République du Bénin) (formerly known as Dahomey The Kingdom of Dahomey () was a West African kingdom located within present-day Benin Benin ( , ; french: ...
was a manufacturer of glass and glass beads. Glass was used extensively in Europe during the
Middle Ages In the history of Europe The history of Europe concerns itself with the discovery and collection, the study, organization and presentation and the interpretation of past events and affairs of the people of Europe since the beginning of ...
. Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites. From the 10th century onwards, glass was employed in
stained glass windows 300px, Outside-view of a stained glass of the Sint-Petrus-en-Pauluskerk from Ostend (Belgium), built between 1899 and 1908 The term stained glass refers to coloured glass as a material and to works created from it. Throughout its thousand-year ...

stained glass windows
of churches and
cathedrals A cathedral is a church (building), church that contains the ''cathedra'' () of a bishop, thus serving as the central church of a diocese, Annual Conference, conference, or episcopate. Churches with the function of "cathedral" are usually speci ...
, with famous examples at
Chartres Cathedral Chartres Cathedral, also known as the Cathedral of Our Lady of Chartres (french: Cathédrale Notre-Dame de Chartres), is a Roman Catholic church architecture, church in Chartres, France, about southwest of Paris, and is the seat of the List of b ...

Chartres Cathedral
and the
Basilica of Saint Denis The Basilica of Saint-Denis (french: Basilique royale de Saint-Denis, links=no, now formally known as the ) is a large former medieval abbey church and present cathedral in the city of Saint-Denis, a northern suburb of Paris Paris () is ...
. By the 14th century, architects were designing buildings with walls of
stained glass The term stained glass refers to coloured glass as a material and to works created from it. Throughout its thousand-year history, the term has been applied almost exclusively to the windows of churches and other significant religious buildings ...

stained glass
such as
Sainte-Chapelle The Sainte-Chapelle (; en, Holy Chapel) is a royal chapel in the Gothic Gothic or Gothics may refer to: People and languages *Goths or Gothic people, the ethnonym of a group of East Germanic tribes **Gothic language, an extinct East Germanic ...

Sainte-Chapelle
, Paris, (1203–1248) and the East end of
Gloucester Cathedral Gloucester Cathedral, formally the Cathedral Church of St Peter and the Holy and Indivisible Trinity, in Gloucester, England Gloucester ( ) is a cathedral city and the county town of Gloucestershire in the South West of England. Gloucester lie ...

Gloucester Cathedral
. With the change in architectural style during the
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in ...
period in Europe, the use of large stained glass windows became much less prevalent, although stained glass had a major revival with
Gothic Revival architecture Gothic Revival (also referred to as Victorian Gothic, neo-Gothic, or Gothick) is an that began in the late 1740s in England. The movement gained momentum and expanded in the first half of the 19th century, as increasingly serious and learned ad ...
in the 19th century. During the 13th century, the island of
Murano Murano is a series of islands linked by bridges in the Venetian Lagoon The Venetian Lagoon ( it, Laguna di Venezia; vec, Łaguna de Venesia) is an enclosed bay of the Adriatic Sea, in northern Italy, in which the city of Venice is situate ...

Murano
,
Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy Italy ( it, Italia ), officially the Italian Republic ( it, Repubblica Italiana, links=no ), is a country consisting of delimited by the and surrounding ...

Venice
, became a centre for glass making, building on medieval techniques to produce colourful ornamental pieces in large quantities.
Murano glass Venetian glass () is thought to have been made for over 1,500 years, and production has been concentrated on the Venetian island of Murano since the 13th century. Today Murano is known for its art glass, but it has a long history of innovations ...

Murano glass
makers developed the exceptionally clear colourless glass
cristallo Cristallo is a glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass i ...

cristallo
, so called for its resemblance to natural crystal, which was extensively used for windows, mirrors, ships' lanterns, and lenses. In the 13th, 14th, and 15th centuries, enamelling and
gilding Gilding is a decorative technique for applying a very thin coating of gold Gold is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an ...
on glass vessels was perfected in Egypt and Syria. Towards the end of the 17th century,
Bohemia Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region Historical regions (or historical areas) are geographical Geography (from Greek Greek may refer to: Greece Anything of, from, ...

Bohemia
became an important region for glass production, remaining so until the start of the 20th century. By the 17th century, glass in the Venetian tradition was also being produced in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest of England and the Celtic Sea to the southwest. E ...

England
. In about 1675, George Ravenscroft invented
lead crystal Lead glass, commonly called crystal, is a variety of glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window ...
glass, with cut glass becoming fashionable in the 18th century. Ornamental glass objects became an important art medium during the
Art Nouveau Art Nouveau (; ) is an international style Style is a manner of doing or presenting things and may refer to: * Architectural style, the features that make a building or structure historically identifiable * Design, the process of creating som ...
period in the late 19th century. Throughout the 20th century, new
mass production Mass production, also known as flow production or continuous production, is the production of substantial amounts of standardized Standardization or standardisation is the process of implementing and developing technical standard A techni ...
techniques led to widespread availability of glass in much larger amounts, making it practical as a building material and enabling new applications of glass. In the 1920s a mould-etch process was developed, in which art was etched directly into the mould, so that each cast piece emerged from the mould with the image already on the surface of the glass. This reduced manufacturing costs and, combined with a wider use of coloured glass, led to cheap glassware in the 1930s, which later became known as
Depression glass Depression glass is glassware made in the period 1929–1939, often clear or colored translucent machine-made glassware that was distributed free, or at low cost, in the United States and Canada around the time of the Great Depression The ...
. In the 1950s, ,
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest of England and the Celtic Sea to the southwest. E ...

England
, developed the
float glass Float glass is a sheet of glass Glass is a non- crystalline, often transparency and translucency, transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optic ...
process, producing high-quality distortion-free flat sheets of glass by floating on molten
tin Tin is a with the Sn (from la, ) and  50. Tin is a silvery-colored metal that characteristically has a faint yellow hue. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent ...

tin
. Modern multi-story buildings are frequently constructed with
curtain walls Curtain wall may refer to: * Curtain wall (architecture), the outer skin of a modern building * Curtain wall (fortification), the outer wall of a castle or defensive wall between two bastions {{Authority control Glass, Amorphous solids Dielectrics Materials Packaging materials Sculpture materials Windows