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89-463: The Upper Falls of the Yellowstone River ( 44°42′46″N 110°29′59″W  /  44.71278°N 110.49972°W  / 44.71278; -110.49972 ) are 109 feet (33 m) high. The brink of Upper Falls marks the junction between a hard rhyolite lava flow and weaker glassy lava that has been more heavily eroded. Cascading from the 590,000 year old Canyon Rhyolite lava flow, Lower Falls of

178-405: A glass (or vitreous solid) is a non-crystalline solid formed by rapid melt quenching . However, the term "glass" is often defined in a broader sense, to describe any non-crystalline ( amorphous ) solid that exhibits a glass transition when heated towards the liquid state. Glass is an amorphous solid . Although the atomic-scale structure of glass shares characteristics of the structure of

267-648: A soil amendment . Rhyolite is an extrusive igneous rock, formed from magma rich in silica that is extruded from a volcanic vent to cool quickly on the surface rather than slowly in the subsurface. It is generally light in color due to its low content of mafic minerals, and it is typically very fine-grained ( aphanitic ) or glassy . An extrusive igneous rock is classified as rhyolite when quartz constitutes 20% to 60% by volume of its total content of quartz, alkali feldspar , and plagioclase ( QAPF ) and alkali feldspar makes up 35% to 90% of its total feldspar content. Feldspathoids are not present. This makes rhyolite

356-457: A soil amendment . Rhyolitic tuff was used extensively for construction in ancient Rome and has been used in construction in modern Europe. Volcanic rocks : Subvolcanic rocks : Plutonic rocks : Picrite basalt Peridotite Basalt Diabase (Dolerite) Gabbro Andesite Microdiorite Diorite Dacite Microgranodiorite Granodiorite Rhyolite Microgranite Granite Glass Glass

445-436: A supercooled liquid , glass exhibits all the mechanical properties of a solid. As in other amorphous solids , the atomic structure of a glass lacks the long-range periodicity observed in crystalline solids . Due to chemical bonding constraints, glasses do possess a high degree of short-range order with respect to local atomic polyhedra . The notion that glass flows to an appreciable extent over extended periods well below

534-809: A turquoise colour in glass, in contrast to copper(I) oxide (Cu 2 O) which gives a dull red-brown colour. Soda–lime sheet glass is typically used as a transparent glazing material, typically as windows in external walls of buildings. Float or rolled sheet glass products are cut to size either by scoring and snapping the material, laser cutting , water jets , or diamond-bladed saw. The glass may be thermally or chemically tempered (strengthened) for safety and bent or curved during heating. Surface coatings may be added for specific functions such as scratch resistance, blocking specific wavelengths of light (e.g. infrared or ultraviolet ), dirt-repellence (e.g. self-cleaning glass ), or switchable electrochromic coatings. Structural glazing systems represent one of

623-485: A clear "ring" sound when struck. However, lead glass cannot withstand high temperatures well. Lead oxide also facilitates the solubility of other metal oxides and is used in coloured glass. The viscosity decrease of lead glass melt is very significant (roughly 100 times in comparison with soda glass); this allows easier removal of bubbles and working at lower temperatures, hence its frequent use as an additive in vitreous enamels and glass solders . The high ionic radius of

712-415: A composition very close to the water-saturated granite eutectic and with extreme enrichment in most incompatible elements . However, they are highly depleted in strontium , barium , and europium . They are interpreted as products of repeated melting and freezing of granite in the subsurface. HSRs typically erupt in large caldera eruptions. Rhyolite is common along convergent plate boundaries , where

801-443: A green tint in thick sections. Manganese dioxide (MnO 2 ), which gives glass a purple colour, may be added to remove the green tint given by FeO. FeO and chromium(III) oxide (Cr 2 O 3 ) additives are used in the production of green bottles. Iron (III) oxide , on the other-hand, produces yellow or yellow-brown glass. Low concentrations (0.025 to 0.1%) of cobalt oxide (CoO) produce rich, deep blue cobalt glass . Chromium

890-465: A height of 308 feet. Today, there are numerous vantage points for viewing the falls. The Canyon loop road skirts north rim of the canyon with several vehicle parking areas. One trail leads down to the Brink of Lower Falls, a steep third of a mile (600 m). Uncle Tom's Trail descends from the east down a series of stairs attached to the cliffs. As of 2022 it was closed. The Lower Falls area is located just to

979-408: A human timescale. Silicon dioxide (SiO 2 ) is a common fundamental constituent of glass. Fused quartz is a glass made from chemically pure silica. It has very low thermal expansion and excellent resistance to thermal shock , being able to survive immersion in water while red hot, resists high temperatures (1000–1500 °C) and chemical weathering, and is very hard. It is also transparent to

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1068-405: A lighter alternative to traditional glass. Molecular liquids, electrolytes , molten salts , and aqueous solutions are mixtures of different molecules or ions that do not form a covalent network but interact only through weak van der Waals forces or transient hydrogen bonds . In a mixture of three or more ionic species of dissimilar size and shape, crystallization can be so difficult that

1157-561: A long period at a temperature just insufficient to cause fusion. In this way, the crystalline, devitrified material, known as Réaumur's glass porcelain is produced. Although generally transparent to visible light, glasses may be opaque to other wavelengths of light . While silicate glasses are generally opaque to infrared wavelengths with a transmission cut-off at 4 μm, heavy-metal fluoride and chalcogenide glasses are transparent to infrared wavelengths of 7 to 18 μm. The addition of metallic oxides results in different coloured glasses as

1246-738: A map showing the location of the falls. The Cook–Folsom–Peterson Expedition , a private group of three explorers named the falls in 1869. The earliest images of the falls were drawn by Private Charles Moore, a member of the U.S. Army escort of the Washburn-Langford-Doane Expedition which explored the Yellowstone River in August–September 1870. During the Hayden Expedition of 1871, the falls were documented in photographs by William Henry Jackson and later in paintings by Thomas Moran . In January 1887, Frank Jay Haynes took

1335-482: A mass of hot semi-molten glass, inflating it into a bubble using a hollow blowpipe, and forming it into the required shape by blowing, swinging, rolling, or moulding. While hot, the glass can be worked using hand tools, cut with shears, and additional parts such as handles or feet attached by welding. Flat glass for windows and similar applications is formed by the float glass process, developed between 1953 and 1957 by Sir Alastair Pilkington and Kenneth Bickerstaff of

1424-561: A natural glass or vitrophyre, also called obsidian . Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations , spherulitic , nodular , and lithophysal structures. Some rhyolite is highly vesicular pumice . Peralkaline rhyolites (rhyolites unusually rich in alkali metals) include comendite and pantellerite . Peralkalinity has significant effects on lava flow morphology and mineralogy , such that peralkaline rhyolites can be 10–30 times more fluid than typical calc-alkaline rhyolites. As

1513-453: A non-crystalline intergranular phase of grain boundaries . Glass-ceramics exhibit advantageous thermal, chemical, biological, and dielectric properties as compared to metals or organic polymers. The most commercially important property of glass-ceramics is their imperviousness to thermal shock. Thus, glass-ceramics have become extremely useful for countertop cooking and industrial processes. The negative thermal expansion coefficient (CTE) of

1602-401: A plastic resin with glass fibres . It is made by melting glass and stretching the glass into fibres. These fibres are woven together into a cloth and left to set in a plastic resin. Fibreglass has the properties of being lightweight and corrosion resistant and is a good insulator enabling its use as building insulation material and for electronic housing for consumer products. Fibreglass

1691-462: A refractive index of 1.4 to 2.4, and an Abbe number (which characterises dispersion) of 15 to 100. The refractive index may be modified by high-density (refractive index increases) or low-density (refractive index decreases) additives. Glass transparency results from the absence of grain boundaries which diffusely scatter light in polycrystalline materials. Semi-opacity due to crystallization may be induced in many glasses by maintaining them for

1780-587: A result of their increased fluidity, they are able to form small-scale flow folds, lava tubes and thin dikes. Peralkaline rhyolites erupt at relatively high temperatures of more than 1,200 °C (2,190 °F). They comprise bimodal shield volcanoes at hotspots and rifts (e.g. Rainbow Range , Ilgachuz Range and Level Mountain in British Columbia , Canada). Eruptions of rhyolite lava are relatively rare compared to eruptions of less felsic lavas. Only four eruptions of rhyolite have been recorded since

1869-633: A result, many eruptions of rhyolite are highly explosive, and rhyolite occurs more frequently as pyroclastic rock than as lava flows . Rhyolitic ash flow tuffs are the only volcanic product with volumes rivaling those of flood basalts . Rhyolites also occur as breccias or in lava domes , volcanic plugs , and dikes . Rhyolitic lavas erupt at a relatively low temperature of 800 to 1,000 °C (1,470 to 1,830 °F), significantly cooler than basaltic lavas, which typically erupt at temperatures of 1,100 to 1,200 °C (2,010 to 2,190 °F). Rhyolites that cool too quickly to grow crystals form

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1958-668: A slab of oceanic lithosphere is being subducted into the Earth's mantle beneath overriding oceanic or continental lithosphere . It can sometimes be the predominant igneous rock type in these settings. Rhyolite is more common when the overriding lithosphere is continental rather than oceanic. The thicker continental crust gives the rising magma more opportunity to differentiate and assimilate crustal rock. Rhyolite has been found on islands far from land, but such oceanic occurrences are rare. The tholeiitic magmas erupted at volcanic ocean islands, such as Iceland , can sometimes differentiate all

2047-412: A spinning metal disk. Several alloys have been produced in layers with thicknesses exceeding 1 millimetre. These are known as bulk metallic glasses (BMG). Liquidmetal Technologies sells several zirconium -based BMGs. Batches of amorphous steel have also been produced that demonstrate mechanical properties far exceeding those found in conventional steel alloys. Experimental evidence indicates that

2136-435: A structural analogue of silica, fluoride , aluminate , phosphate , borate , and chalcogenide glasses) have physicochemical properties useful for their application in fibre-optic waveguides in communication networks and other specialised technological applications. Silica-free glasses may often have poor glass-forming tendencies. Novel techniques, including containerless processing by aerodynamic levitation (cooling

2225-413: A structurally metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic 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 where certain thermodynamic variables such as volume , entropy and enthalpy are discontinuous through

2314-518: A wider spectral range than ordinary glass, extending from the visible further into both the UV and IR ranges, and is sometimes used where transparency to these wavelengths is necessary. Fused quartz is used for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, etc. However, its high melting temperature (1723 °C) and viscosity make it difficult to work with. Therefore, normally, other substances (fluxes) are added to lower

2403-418: Is 3.25 × 10 /°C as compared to about 9 × 10 /°C for a typical soda–lime glass ). They are, therefore, less subject to stress caused by thermal expansion and thus less vulnerable to cracking from thermal shock . They are commonly used for e.g. labware , household cookware , and sealed beam car head lamps . The addition of lead(II) oxide into silicate glass lowers the melting point and viscosity of

2492-552: Is a common volcanic glass with high silica (SiO 2 ) content formed when felsic lava extruded from a volcano cools rapidly. Impactite is a form of glass formed by the impact of a meteorite , where Moldavite (found in central and eastern Europe), and Libyan desert glass (found in areas in the eastern Sahara , the deserts of eastern Libya and western Egypt ) are notable examples. Vitrification of quartz can also occur when lightning strikes sand , forming hollow, branching rootlike structures called fulgurites . Trinitite

2581-702: Is a glassy residue formed from the desert floor sand at the Trinity nuclear bomb test site. Edeowie glass , found in South Australia , is proposed to originate from Pleistocene grassland fires, lightning strikes, or hypervelocity impact by one or several asteroids or comets . 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. Glassmaking dates back at least 6000 years, long before humans had discovered how to smelt iron. Archaeological evidence suggests that

2670-418: Is a very powerful colouring agent, yielding dark green. Sulphur combined with carbon and iron salts produces amber glass ranging from yellowish to almost black. A glass melt can also acquire an amber colour from a reducing combustion atmosphere. Cadmium sulfide produces imperial red , and combined with selenium can produce shades of yellow, orange, and red. Addition of copper(II) oxide (CuO) produces

2759-449: Is achieved by homogenizing the raw materials mixture ( glass batch ), stirring the melt, and crushing and re-melting the first melt. The obtained glass is usually annealed to prevent breakage during processing. Colour in glass may be obtained by addition of homogenously distributed electrically charged ions (or colour centres ). While ordinary soda–lime glass appears colourless in thin section, iron(II) oxide (FeO) impurities produce

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2848-543: Is an amorphous ( non-crystalline ) solid. Because it is often transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware , and optics . Some common objects made of glass are named after the material, e.g. "glass" , " glasses ", " magnifying glass ". Glass is most often formed by rapid cooling ( quenching ) of the molten form. Some glasses such as volcanic glass are naturally occurring, and obsidian has been used to make arrowheads and knives since

2937-676: Is extensively used for fibreglass , used for making glass-reinforced plastics (boats, fishing rods, etc.), top-of-stove cookware, and halogen bulb glass. The addition of barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eyeglasses. Iron can be incorporated into glass to absorb infrared radiation, for example in heat-absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs ultraviolet wavelengths. Fluorine lowers

3026-455: Is in widespread use in optical systems due to its ability to refract, reflect, and transmit light following geometrical optics . The most common and oldest applications of glass in optics are as lenses , windows , mirrors , and prisms . The key optical properties refractive index , dispersion , and transmission , of glass are strongly dependent on chemical composition and, to a lesser degree, its thermal history. Optical glass typically has

3115-481: Is incorrect, as once solidified, glass stops flowing. The sags and ripples observed in old glass were already there the day it was made; manufacturing processes used in the past produced sheets with imperfect surfaces and non-uniform thickness (the near-perfect float glass used today only became widespread in the 1960s). A 2017 study computed the rate of flow of the medieval glass used in Westminster Abbey from

3204-462: Is more often erupted as pyroclastic rock than as lava flows . Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been used extensively for construction. Obsidian , which is rhyolitic volcanic glass , has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive , in concrete , and as

3293-901: Is produced by forcing molten glass through a fine mesh by centripetal force and breaking the extruded glass fibres into short lengths using a stream of high-velocity air. The fibres are bonded with an adhesive spray and the resulting wool mat is cut and packed in rolls or panels. Besides common silica-based glasses many other inorganic and organic materials may also form glasses, including metals , aluminates , phosphates , borates , chalcogenides , fluorides , germanates (glasses based on GeO 2 ), tellurites (glasses based on TeO 2 ), antimonates (glasses based on Sb 2 O 3 ), arsenates (glasses based on As 2 O 3 ), titanates (glasses based on TiO 2 ), tantalates (glasses based on Ta 2 O 5 ), nitrates , carbonates , plastics , acrylic , and many other substances. Some of these glasses (e.g. Germanium dioxide (GeO 2 , Germania), in many respects

3382-461: Is stronger than most metals, with a theoretical tensile strength for pure, flawless glass estimated at 14 to 35 gigapascals (2,000,000 to 5,100,000 psi) due to its ability to undergo reversible compression without fracture. However, the presence of scratches, bubbles, and other microscopic flaws lead to a typical range of 14 to 175 megapascals (2,000 to 25,400 psi) in most commercial glasses. Several processes such as toughening can increase

3471-408: Is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead, the disordered atomic configuration of the supercooled liquid is frozen into the solid state at T g . 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

3560-521: Is the most silica -rich of volcanic rocks . It is generally glassy or fine-grained ( aphanitic ) in texture , but may be porphyritic , containing larger mineral crystals ( phenocrysts ) in an otherwise fine-grained groundmass . The mineral assemblage is predominantly quartz , sanidine , and plagioclase . It is the extrusive equivalent of granite . Its high silica content makes rhyolitic magma extremely viscous . This favors explosive eruptions over effusive eruptions , so this type of magma

3649-436: Is transparent, easily formed, and most suitable for window glass and tableware. However, it has a high thermal expansion and poor resistance to heat. Soda–lime glass is typically used for windows , bottles , light bulbs , and jars . Borosilicate glasses (e.g. Pyrex , Duran ) typically contain 5–13% boron trioxide (B 2 O 3 ). Borosilicate glasses have fairly low coefficients of thermal expansion (7740 Pyrex CTE

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3738-513: The Late Bronze Age , there was a rapid growth in glassmaking technology in Egypt and Western Asia . Archaeological finds from this period include coloured glass ingots , vessels, and beads. Much early glass production relied on grinding techniques borrowed from stoneworking , such as grinding and carving glass in a cold state. The term glass has its origins in the late Roman Empire , in

3827-525: The Renaissance 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 in the 19th century. During the 13th century, the island of Murano , Venice , became a centre for glass making, building on medieval techniques to produce colourful ornamental pieces in large quantities. Murano glass makers developed

3916-527: The Roman glass making centre at Trier (located in current-day Germany) where the late-Latin term glesum originated, likely from a Germanic word for a transparent , lustrous substance. Glass objects have been recovered across the Roman Empire in domestic, funerary , and industrial contexts, as well as trade items in marketplaces in distant provinces. Examples of Roman glass have been found outside of

4005-1259: The Stone Age . Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia , Egypt , or Syria . The earliest known glass objects were beads , perhaps created accidentally during metalworking or the production of faience , which is a form of pottery using lead glazes. 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. Soda–lime glass , containing around 70% silica , accounts for around 90% of modern manufactured glass. 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. The refractive , reflective and transmission properties of glass make glass suitable for manufacturing optical lenses , prisms , and optoelectronics materials. Extruded glass fibres have applications as optical fibres in communications networks, thermal insulating material when matted as glass wool to trap air, or in glass-fibre reinforced plastic ( fibreglass ). The standard definition of

4094-465: The dielectric constant of glass. Fluorine is highly electronegative and lowers the polarizability of the material. Fluoride silicate glasses are used in the manufacture of integrated circuits as an insulator. Glass-ceramic materials contain both non-crystalline glass and crystalline ceramic phases. They are formed by controlled nucleation and partial crystallisation of a base glass by heat treatment. Crystalline grains are often embedded within

4183-436: The glass batch preparation and mixing, the raw materials are transported to the furnace. Soda–lime glass for mass production is melted in glass-melting furnaces . Smaller-scale furnaces for speciality glasses include electric melters, pot furnaces, and day tanks. After melting, homogenization and refining (removal of bubbles), the glass is formed . This may be achieved manually by glassblowing , which involves gathering

4272-501: The 10th century onwards, glass was employed in stained glass windows of churches and cathedrals , with famous examples at Chartres Cathedral and the Basilica of Saint-Denis . By the 14th century, architects were designing buildings with walls of stained glass such as Sainte-Chapelle , Paris, (1203–1248) and the East end of Gloucester Cathedral . With the change in architectural style during

4361-461: The 1930s, which later became known as Depression glass . In the 1950s, Pilkington Bros. , England , developed the float glass process, producing high-quality distortion-free flat sheets of glass by floating on molten tin . Modern multi-story buildings are frequently constructed with curtain walls made almost entirely of glass. Laminated glass has been widely applied to vehicles for windscreens. Optical glass for spectacles has been used since

4450-681: The Middle Ages. The production of lenses has become increasingly proficient, aiding astronomers as well as having other applications in medicine and science. Glass is also employed as the aperture cover in many solar energy collectors. In the 21st century, glass manufacturers have developed different brands of chemically strengthened glass for widespread application in touchscreens for smartphones , tablet computers , and many other types of information appliances . These include Gorilla Glass , developed and manufactured by Corning , AGC Inc. 's Dragontrail and Schott AG 's Xensation. Glass

4539-540: The Pb ion renders it highly immobile and hinders the movement of other ions; lead glasses therefore have high electrical resistance, about two orders of magnitude higher than soda–lime glass (10 vs 10  Ω⋅cm, DC at 250 °C). Aluminosilicate glass typically contains 5–10% alumina (Al 2 O 3 ). Aluminosilicate glass tends to be more difficult to melt and shape compared to borosilicate compositions but has excellent thermal resistance and durability. Aluminosilicate glass

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4628-617: The R field of the TAS diagram . The alkali feldspar in rhyolites is sanidine or, less commonly, orthoclase . It is rarely anorthoclase . These feldspar minerals sometimes are present as phenocrysts. The plagioclase is usually sodium -rich ( oligoclase or andesine ). Cristobalite and trydimite are sometimes present along with the quartz. Biotite , augite , fayalite , and hornblende are common accessory minerals. Due to their high content of silica and low iron and magnesium contents, rhyolitic magmas form highly viscous lavas . As

4717-530: The UK's Pilkington Brothers, who created a continuous ribbon of glass using a molten tin bath on which the molten glass flows unhindered under the influence of gravity. The top surface of the glass is subjected to nitrogen under pressure to obtain a polished finish. Container glass for common bottles and jars is formed by blowing and pressing methods. This glass is often slightly modified chemically (with more alumina and calcium oxide) for greater water resistance. Once

4806-517: The Yellowstone River is the largest volume waterfall in the Rocky Mountains of the United States. These falls ( 44°43′05″N 110°29′46″W  /  44.71806°N 110.49611°W  / 44.71806; -110.49611 ) are 308 feet (94 m) high, or nearly twice as high as Niagara Falls . The volume of water flowing over Lower Falls can vary from 680 cu ft/s (19 m/s) in

4895-719: The action of water, making it an ideal material for the manufacture of containers for foodstuffs and most chemicals. Nevertheless, although usually highly resistant to chemical attack, glass will corrode or dissolve under some conditions. The materials that make up a particular glass composition affect how quickly the glass corrodes. Glasses containing a high proportion of alkali or alkaline earth elements are more susceptible to corrosion than other glass compositions. The density of glass varies with chemical composition with values ranging from 2.2 grams per cubic centimetre (2,200 kg/m ) for fused silica to 7.2 grams per cubic centimetre (7,200 kg/m ) for dense flint glass. Glass

4984-467: The autumn, to 8,400 cu ft/s (240 m/s) at peak runoff in late springtime. The flow rate of Lower Falls is much less than that of Niagara Falls, as the Yellowstone River is only 70 feet (21 m) wide at the point at the brink, whereas the Niagara River is 2,600 feet (790 m) in width as it approaches the crest line of Horseshoe Falls. It is likely that Native American tribes knew of

5073-411: The cost factor has a low priority. In the laboratory mostly pure chemicals are used. Care must be taken that the raw materials have not reacted with moisture or other chemicals in the environment (such as alkali or alkaline earth metal oxides and hydroxides, or boron oxide ), or that the impurities are quantified (loss on ignition). Evaporation losses during glass melting should be considered during

5162-427: The crystalline ceramic phase can be balanced with the positive CTE of the glassy phase. At a certain point (~70% crystalline) the glass-ceramic has a net CTE near zero. This type of glass-ceramic exhibits excellent mechanical properties and can sustain repeated and quick temperature changes up to 1000 °C. Fibreglass (also called glass fibre reinforced plastic, GRP) is a composite material made by reinforcing

5251-683: The desired form is obtained, glass is usually annealed for the removal of stresses and to increase the glass's hardness and durability. Surface treatments, coatings or lamination may follow to improve the chemical durability ( glass container coatings , glass container internal treatment ), strength ( toughened glass , bulletproof glass , windshields ), or optical properties ( insulated glazing , anti-reflective coating ). New chemical glass compositions or new treatment techniques can be initially investigated in small-scale laboratory experiments. The raw materials for laboratory-scale glass melts are often different from those used in mass production because

5340-462: The exceptionally clear colourless glass 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 on glass vessels were perfected in Egypt and Syria. Towards the end of the 17th century, Bohemia became an important region for glass production, remaining so until

5429-504: The extrusive equivalent of granite. However, while the IUGS recommends classifying volcanic rocks on the basis of their mineral composition whenever possible, volcanic rocks are often glassy or so fine-grained that mineral identification is impractical. The rock must then be classified chemically based on its content of silica and alkali metal oxides ( K 2 O plus Na 2 O ). Rhyolite is high in silica and total alkali metal oxides, placing it in

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5518-564: The falls for centuries. Captain William Clark of the Lewis and Clark Expedition made a note in his journal about hearing of the falls but did not believe the story. The first European to see the falls was likely French fur trapper Baptise Ducharme who claimed to see the falls in 1824, 1826 and 1839. Jim Bridger and fellow explorer James Gremmell claimed they visited the falls in 1846. In 1851, Bridger provided missionary Father Pierre-Jean De Smet

5607-454: The first true synthetic glass was made in Lebanon and the coastal north Syria , Mesopotamia or ancient Egypt . 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 . Early glass

5696-432: The first winter photographs of Lower Falls. Over the years the estimates of the height of Lower Falls has varied dramatically. In 1851 Jim Bridger estimated its height at 250 feet. One outrageous newspaper story from 1867 placed its height at "thousands of feet". A map from 1869 gives the falls its current name of Lower Falls for the first time and estimates the height at 350 feet. However the current map lists Lower Falls at

5785-733: The former Roman Empire in China , the Baltics , the Middle East , and India . The Romans perfected cameo glass , produced by etching and carving through fused layers of different colours to produce a design in relief on the glass object. In post-classical West Africa, Benin was a manufacturer of glass and glass beads. Glass was used extensively in Europe during the Middle Ages . Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites. From

5874-555: The glass and melt phases. Important polymer glasses include amorphous and glassy pharmaceutical compounds. These are useful because the solubility of the compound is greatly increased when it is amorphous compared to the same crystalline composition. Many emerging pharmaceuticals are practically insoluble in their crystalline forms. Many polymer thermoplastics familiar to everyday use are glasses. For many applications, like glass bottles or eyewear , polymer glasses ( acrylic glass , polycarbonate or polyethylene terephthalate ) are

5963-493: The glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. However, the equilibrium theory of phase transformations does not hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids. Glass can form naturally from volcanic magma. Obsidian

6052-406: The glass transition temperature is not supported by empirical research or theoretical analysis (see viscosity in solids ). Though atomic motion at glass surfaces can be observed, and viscosity on the order of 10 –10 Pa s can be measured in glass, such a high value reinforces the fact that glass would not change shape appreciably over even large periods of time. For melt quenching, if the cooling

6141-458: The liquid can easily be supercooled into a glass. Examples include LiCl: R H 2 O (a solution of lithium chloride salt and water molecules) in the composition range 4< R <8. sugar glass , or Ca 0.4 K 0.6 (NO 3 ) 1.4 . Glass electrolytes in the form of Ba-doped Li-glass and Ba-doped Na-glass have been proposed as solutions to problems identified with organic liquid electrolytes used in modern lithium-ion battery cells. Following

6230-481: The melt whilst it floats on a gas stream) or splat quenching (pressing the melt between two metal anvils or rollers), may be used to increase the cooling rate or to reduce crystal nucleation triggers. In the past, small batches of amorphous metals with high surface area configurations (ribbons, wires, films, etc.) have been produced through the implementation of extremely rapid rates of cooling. Amorphous metal wires have been produced by sputtering molten metal onto

6319-433: The melt. The high density of lead glass (silica + lead oxide (PbO) + potassium oxide (K 2 O) + soda (Na 2 O) + zinc oxide (ZnO) + alumina) results in a high electron density, and hence high refractive index, making the look of glassware more brilliant and causing noticeably more specular reflection and increased optical dispersion . Lead glass has a high elasticity, making the glassware more workable and giving rise to

6408-619: The melting temperature and simplify glass processing. Sodium carbonate (Na 2 CO 3 , "soda") is a common additive and acts to lower the glass-transition temperature. However, sodium silicate is water-soluble , so lime (CaO, calcium oxide , generally obtained from limestone ), along with magnesium oxide (MgO), and aluminium oxide (Al 2 O 3 ), are commonly added to improve chemical durability. Soda–lime glasses (Na 2 O) + lime (CaO) + magnesia (MgO) + alumina (Al 2 O 3 ) account for over 75% of manufactured glass, containing about 70 to 74% silica by weight. Soda–lime–silicate glass

6497-410: The metallic ions will absorb wavelengths of light corresponding to specific colours. In the manufacturing process, glasses can be poured, formed, extruded and moulded into forms ranging from flat sheets to highly intricate shapes. The finished product is brittle but can be laminated or tempered to enhance durability. Glass is typically inert, resistant to chemical attack, and can mostly withstand

6586-409: The most significant architectural innovations of modern times, where glass buildings now often dominate the skylines of many modern cities . These systems use stainless steel fittings countersunk into recesses in the corners of the glass panels allowing strengthened panes to appear unsupported creating a flush exterior. Structural glazing systems have their roots in iron and glass conservatories of

6675-434: The rhyolite appears to be a product of melting of crustal sedimentary rock. Water vapor plays an important role in lowering the melting point of silicic rock, and some rhyolitic magmas may have a water content as high as 7–8 weight percent. High-silica rhyolite (HSR), with a silica content of 75 to 77·8% SiO 2 , forms a distinctive subgroup within the rhyolites. HSRs are the most evolved of all igneous rocks, with

6764-424: The selection of the raw materials, e.g., sodium selenite may be preferred over easily evaporating selenium dioxide (SeO 2 ). Also, more readily reacting raw materials may be preferred over relatively inert ones, such as aluminium hydroxide (Al(OH) 3 ) over alumina (Al 2 O 3 ). Usually, the melts are carried out in platinum crucibles to reduce contamination from the crucible material. Glass homogeneity

6853-807: The south and east of Canyon Village in Yellowstone National Park. A one-way loop drive starting south from Canyon Junction takes one to the brink of the Grand Canyon of the Yellowstone and offers four viewpoints, with the first stop at the trail that leads to the top of the Lower Falls. The one-way drive continues east and north past the other viewpoints, rejoining the main Grand Loop road from the east at Canyon Junction once more. Rhyolite Rhyolite ( / ˈ r aɪ . ə l aɪ t / RY -ə-lyte )

6942-587: The start of the 20th century. By the 17th century, glass in the Venetian tradition was also being produced in England . In about 1675, George Ravenscroft invented lead crystal glass, with cut glass becoming fashionable in the 18th century. Ornamental glass objects became an important art medium during the Art Nouveau period in the late 19th century. Throughout the 20th century, new mass production techniques led to

7031-561: The start of the 20th century: at the St. Andrew Strait volcano in Papua New Guinea and Novarupta volcano in Alaska as well as at Chaitén and Cordón Caulle volcanoes in southern Chile . The eruption of Novarupta in 1912 was the largest volcanic eruption of the 20th century, and began with explosive volcanism that later transitioned to effusive volcanism and the formation of a rhyolite dome in

7120-469: The strength of glass. Carefully drawn flawless glass fibres can be produced with a strength of up to 11.5 gigapascals (1,670,000 psi). The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption

7209-460: The system Al-Fe-Si may undergo a first-order transition to an amorphous form (dubbed "q-glass") on rapid cooling from the melt. Transmission electron microscopy (TEM) images indicate that q-glass nucleates from the melt as discrete particles with uniform spherical growth in all directions. While x-ray diffraction reveals the isotropic nature of q-glass, a nucleation barrier exists implying an interfacial discontinuity (or internal surface) between

7298-450: The vent. Rhyolite magmas can be produced by igneous differentiation of a more mafic (silica-poor) magma, through fractional crystallization or by assimilation of melted crustal rock ( anatexis ). Associations of andesites , dacites , and rhyolites in similar tectonic settings and with similar chemistry suggests that the rhyolite members were formed by differentiation of mantle-derived basaltic magmas at shallow depths. In other cases,

7387-642: The way to rhyolite, and about 8% of the volcanic rock in Iceland is rhyolite. However, this is unusual, and the Hawaiian Islands (for example) have no known occurrences of rhyolite. The alkaline magmas of volcanic ocean islands will very occasionally differentiate all the way to peralkaline rhyolites, but differentiation usually ends with trachyte . Small volumes of rhyolite are sometimes erupted in association with flood basalts , late in their history and where central volcanic complexes develop. The name rhyolite

7476-451: The 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

7565-402: The year 1268. The study found that the room temperature viscosity of this glass was roughly 10   Pa · s which is about 10 times less viscous than a previous estimate made in 1998, which focused on soda-lime silicate glass. Even with this lower viscosity, the study authors calculated that the maximum flow rate of medieval glass is 1 nm per billion years, making it impossible to observe in

7654-630: Was introduced into geology in 1860 by the German traveler and geologist Ferdinand von Richthofen from the Greek word rhýax ("a stream of lava") and the rock name suffix "-lite". In North American pre-historic times , rhyolite was quarried extensively in what is now eastern Pennsylvania . Among the leading quarries was the Carbaugh Run Rhyolite Quarry Site in Adams County . Rhyolite

7743-559: Was mined there starting 11,500 years ago. Tons of rhyolite were traded across the Delmarva Peninsula , because the rhyolite kept a sharp point when knapped and was used to make spear points and arrowheads. Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times. Obsidian scalpels have been investigated for use in delicate surgery. Pumice, also typically of rhyolitic composition, finds important uses as an abrasive , in concrete , and as

7832-510: Was originally used in the United Kingdom and United States during World War II to manufacture radomes . Uses of fibreglass include building and construction materials, boat hulls, car body parts, and aerospace composite materials. Glass-fibre wool is an excellent thermal and sound insulation material, commonly used in buildings (e.g. attic and cavity wall insulation ), and plumbing (e.g. pipe insulation ), and soundproofing . It

7921-539: 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 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. During

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