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55-438: Originally, the observatory was home to a 20" telescope, given to the department by an avid amateur who lived in central Massachusetts. It was a ⁠ 1 / 10 ⁠ scale model (loosely) of a larger 200" scope. Eventually, a crack was spotted during one of the re- aluminizings of the 20" mirror, and the scope was decommissioned. In the meantime, the department had been granted money—associated with its move from Hasbrouck to

110-433: A reflective substance, to produce a mirror . While the metal is often silver , the term is used for the application of any reflective metal. Most common household mirrors are "back-silvered" or "second-surface", meaning that the light reaches the reflective layer after passing through the glass. A protective layer of paint is usually applied to protect the back side of the reflective surface . This arrangement protects

165-432: A household mirror is often actual silver. A modern "wet" process for silver coating treats the glass with tin(II) chloride to improve the bonding between silver and glass. An activator is applied after the silver has been deposited to harden the tin and silver coatings. A layer of copper may be added for long-term durability. Silver would be ideal for telescope mirrors and other demanding optical applications, since it has

220-402: A layered structure ( space group R 3 m No. 166) whose layers consist of fused, ruffled, six-membered rings. The nearest and next-nearest neighbors form an irregular octahedral complex, with the three atoms in each double layer slightly closer than the three atoms in the next. This relatively close packing leads to a high density of 6.697 g/cm , but the weak bonding between the layers leads to

275-406: A lecture by Herbert Gladstone in 1892, commented that "we only know of antimony at the present day as a highly brittle and crystalline metal, which could hardly be fashioned into a useful vase, and therefore this remarkable 'find' (artifact mentioned above) must represent the lost art of rendering antimony malleable." The British archaeologist Roger Moorey was unconvinced the artifact was indeed

330-451: A process for depositing silver on the rear surface of a piece of glass; this technique gained wide acceptance after Liebig improved it in 1856. The process was further refined and made easier by the chemist Tony Petitjean (1856). This reaction is a variation of the Tollens' reagent for aldehydes. A diamminesilver(I) solution is mixed with a sugar and sprayed onto the glass surface. The sugar

385-501: A sheet of glass is placed in a vacuum chamber with electrically heated nichrome coils that can evaporate aluminum. In a vacuum, the hot aluminum atoms travel in straight lines. When they hit the surface of the mirror, they cool and stick. Some mirror makers evaporate a layer of quartz or beryllia on the mirror; others expose it to pure oxygen or air in an oven so that it will form a tough, clear layer of aluminum oxide . The first tin-coated glass mirrors were produced by applying

440-432: A thin film (thickness in nanometres); thicker samples spontaneously transform into the metallic form. It oxidizes in air and may ignite spontaneously. At 100 °C, it gradually transforms into the stable form. The supposed yellow allotrope of antimony, generated only by oxidation of stibine (SbH 3 ) at −90 °C, is also impure and not a true allotrope; above this temperature and in ambient light, it transforms into

495-440: A tin-mercury amalgam to the glass and heating the piece to evaporate the mercury. The "silvering" on infrared instruments is usually gold. It has the best reflectivity in the infrared spectrum, and has high resistance to oxidation and corrosion. Conversely, a thin gold coating is used to create optical filters which block infrared (by mirroring it back towards the source) while passing visible light. Antimony Antimony

550-617: A vase, mentioning that Selimkhanov, after his analysis of the Tello object (published in 1975), "attempted to relate the metal to Transcaucasian natural antimony" (i.e. native metal) and that "the antimony objects from Transcaucasia are all small personal ornaments." This weakens the evidence for a lost art "of rendering antimony malleable". The Roman scholar Pliny the Elder described several ways of preparing antimony sulfide for medical purposes in his treatise Natural History , around 77 AD. Pliny

605-673: Is stibnite ( Sb 2 S 3 ). Other sulfide minerals include pyrargyrite ( Ag 3 SbS 3 ), zinkenite , jamesonite , and boulangerite . Antimony pentasulfide is non-stoichiometric , which features antimony in the +3 oxidation state and S–S bonds. Several thioantimonides are known, such as [Sb 6 S 10 ] and [Sb 8 S 13 ] . Antimony forms two series of halides : SbX 3 and SbX 5 . The trihalides SbF 3 , SbCl 3 , SbBr 3 , and SbI 3 are all molecular compounds having trigonal pyramidal molecular geometry . The trifluoride SbF 3

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660-472: Is a chemical element ; it has symbol Sb (from Latin stibium ) and atomic number 51. A lustrous grey metal or metalloid , it is found in nature mainly as the sulfide mineral stibnite (Sb 2 S 3 ). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name kohl . The earliest known description of this metalloid in

715-486: Is a scribal corruption of some Arabic form; Meyerhof derives it from ithmid ; other possibilities include athimar , the Arabic name of the metalloid, and a hypothetical as-stimmi , derived from or parallel to the Greek. The standard chemical symbol for antimony (Sb) is credited to Jöns Jakob Berzelius , who derived the abbreviation from stibium . The ancient words for antimony mostly have, as their chief meaning, kohl ,

770-728: Is consumed in flame retardants , 33% in lead–acid batteries , and 8% in plastics. Antimony is mainly used as the trioxide for flame-proofing compounds , always in combination with halogenated flame retardants except in halogen-containing polymers. The flame retarding effect of antimony trioxide is produced by the formation of halogenated antimony compounds, which react with hydrogen atoms, and probably also with oxygen atoms and OH radicals, thus inhibiting fire. Markets for these flame-retardants include children's clothing, toys, aircraft, and automobile seat covers. They are also added to polyester resins in fiberglass composites for such items as light aircraft engine covers. The resin will burn in

825-627: Is more common. Antimony trioxide is formed when antimony is burnt in air. In the gas phase, the molecule of the compound is Sb 4 O 6 , but it polymerizes upon condensing. Antimony pentoxide ( Sb 4 O 10 ) can be formed only by oxidation with concentrated nitric acid . Antimony also forms a mixed-valence oxide, antimony tetroxide ( Sb 2 O 4 ), which features both Sb(III) and Sb(V). Unlike oxides of phosphorus and arsenic , these oxides are amphoteric , do not form well-defined oxoacids , and react with acids to form antimony salts. Antimonous acid Sb(OH) 3

880-715: Is oxidized by silver(I), which is itself reduced to silver(0), i.e. elemental silver , and deposited onto the glass. In 1856-1857 Karl August von Steinheil and Léon Foucault introduced the process of depositing an ultra-thin layer of silver on the front surface of a piece of glass, making the first optical-quality first surface glass mirrors, replacing the use of speculum metal mirrors in reflecting telescopes . These techniques soon became standard for technical equipment. An aluminum vacuum-deposition process invented in 1930 by Caltech physicist and astronomer John Strong , led to most reflecting telescopes shifting to aluminum. Nevertheless, some modern telescopes use silver, such as

935-414: Is possibly a loan word from Arabic or from Egyptian stm . The extraction of antimony from ores depends on the quality and composition of the ore. Most antimony is mined as the sulfide; lower-grade ores are concentrated by froth flotation , while higher-grade ores are heated to 500–600 °C, the temperature at which stibnite melts and separates from the gangue minerals. Antimony can be isolated from

990-403: Is prepared by the reaction of Sb 2 O 3 with HF : It is Lewis acidic and readily accepts fluoride ions to form the complex anions SbF 4 and SbF 5 . Molten SbF 3 is a weak electrical conductor . The trichloride SbCl 3 is prepared by dissolving Sb 2 S 3 in hydrochloric acid : Arsenic sulfides are not readily attacked by

1045-401: Is resistant to attack by acids. The only stable allotrope of antimony under standard conditions is metallic, brittle , silver-white, and shiny. It crystallises in a trigonal cell, isomorphic with bismuth and the gray allotrope of arsenic , and is formed when molten antimony is cooled slowly. Amorphous black antimony is formed upon rapid cooling of antimony vapor, and is only stable as

1100-459: Is stable in air at room temperature but, if heated, it reacts with oxygen to produce antimony trioxide , Sb 2 O 3 . Antimony is a silvery, lustrous gray metalloid with a Mohs scale hardness of 3, which is too soft to mark hard objects. Coins of antimony were issued in China's Guizhou in 1931; durability was poor, and minting was soon discontinued because of its softness and toxicity. Antimony

1155-434: Is the 63rd most abundant element in the crust. Even though this element is not abundant, it is found in more than 100 mineral species. Antimony is sometimes found natively (e.g. on Antimony Peak ), but more frequently it is found in the sulfide stibnite (Sb 2 S 3 ) which is the predominant ore mineral. Antimony compounds are often classified according to their oxidation state: Sb(III) and Sb(V). The +5 oxidation state

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1210-536: Is uncertain, and all suggestions have some difficulty either of form or interpretation. The popular etymology , from ἀντίμοναχός anti-monachos or French antimoine , would mean "monk-killer", which is explained by the fact that many early alchemists were monks, and some antimony compounds were poisonous. Another popular etymology is the hypothetical Greek word ἀντίμόνος antimonos , "against aloneness", explained as "not found as metal", or "not found unalloyed". However, ancient Greek would more naturally express

1265-448: Is unknown, but the conjugate base sodium antimonite ( [Na 3 SbO 3 ] 4 ) forms upon fusing sodium oxide and Sb 4 O 6 . Transition metal antimonites are also known. Antimonic acid exists only as the hydrate HSb(OH) 6 , forming salts as the antimonate anion Sb(OH) 6 . When a solution containing this anion is dehydrated, the precipitate contains mixed oxides. The most important antimony ore

1320-622: Is unlikely to increase in the coming years, according to the Roskill report. No significant antimony deposits in China have been developed for about ten years, and the remaining economic reserves are being rapidly depleted. For antimony-importing regions, such as Europe and the U.S., antimony is considered to be a critical mineral for industrial manufacturing that is at risk of supply chain disruption. With global production coming mainly from China (74%), Tajikistan (8%), and Russia (4%), these sources are critical to supply. Approximately 48% of antimony

1375-615: The Earth's crust was described by the Swedish scientist and local mine district engineer Anton von Swab in 1783; the type-sample was collected from the Sala Silver Mine in the Bergslagen mining district of Sala , Västmanland , Sweden. The medieval Latin form, from which the modern languages and late Byzantine Greek take their names for antimony, is antimonium . The origin of that

1430-652: The Five Colleges , utilizes the observatory to host observing nights on clear nights. The observatory does not receive any external funding. It is part of the College of Natural Sciences/Astronomy, maintained and operated by the UMass Astronomy Department and supported by members of the Five College Astronomy Club. It is possible to see a variety of astronomical bodies at the observatory. Members of

1485-520: The Kepler Space Telescope . The Kepler mirror's silver was deposited using ion assisted evaporation . Silvering aims to produce a non-crystalline coating of amorphous metal (metallic glass), with no visible artifacts from grain boundaries. The most common methods in current use are electroplating , chemical "wet process" deposition, and vacuum deposition . Electroplating of a substrate of glass or other non- conductive material requires

1540-431: The Elder also made a distinction between "male" and "female" forms of antimony; the male form is probably the sulfide, while the female form, which is superior, heavier, and less friable, has been suspected to be native metallic antimony. The Greek naturalist Pedanius Dioscorides mentioned that antimony sulfide could be roasted by heating by a current of air. It is thought that this produced metallic antimony. Antimony

1595-552: The Graduate Research Tower—to buy a small telescope and install it on top of the GRC. The GRC had a small "isolation" pad built onto its roof, which was supposed to be a mount for the scope, accessible via a small open elevator. However, the GRC had terrible noise and gross vibration problems. The isolation pad never worked, and there were too many safety concerns about using the roof of the building for observing. A 16" telescope

1650-671: The West was written in 1540 by Vannoccio Biringuccio . China is the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony from stibnite are roasting followed by reduction with carbon , or direct reduction of stibnite with iron. The most common applications for metallic antimony are in alloys with lead and tin , which have improved properties for solders , bullets, and plain bearings . It improves

1705-462: The best initial front-surface reflectivity in the visible spectrum. However, it quickly oxidizes and absorbs atmospheric sulfur to create a dark, low-reflectivity tarnish. The "silvering" on precision optical instruments such as telescopes is usually aluminum. Although aluminum also oxidizes quickly, the thin aluminum oxide (sapphire) layer is transparent, and so the high-reflectivity underlying aluminum stays visible. In modern aluminum silvering,

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1760-443: The crude antimony sulfide by reduction with scrap iron: The sulfide is converted to an oxide by roasting. The product is further purified by vaporizing the volatile antimony(III) oxide, which is recovered. This sublimate is often used directly for the main applications, impurities being arsenic and sulfide. Antimony is isolated from the oxide by a carbothermal reduction: The lower-grade ores are reduced in blast furnaces while

1815-416: The deposition of a thin layer of conductive but transparent material, such as carbon. This layer tends to reduce the adhesion between the metal and the substrate. Chemical deposition can result in better adhesion, directly or by pre-treatment of the surface. Vacuum deposition can produce very uniform coating with very precisely controlled thickness. The reflective layer on a second surface mirror such as

1870-460: The discovery of metallic antimony. The book Currus Triumphalis Antimonii (The Triumphal Chariot of Antimony), describing the preparation of metallic antimony, was published in Germany in 1604. It was purported to be written by a Benedictine monk, writing under the name Basilius Valentinus in the 15th century; if it were authentic, which it is not, it would predate Biringuccio. The metal antimony

1925-551: The dome there. The 16" was a major improvement in usability. At present, the 20" may still be stored in the Astronomy Research Facility, but the drive was most likely not kept. Special thanks to Professor Thomas Arny for much of the recent history of the facility. The observatory does not currently have a regular schedule. It was regularly open for public viewing on Thursday nights until at least 2011. The Five College Astronomy Club, consisting of students belonging to

1980-665: The early 10th century, the Persian scientist al-Razi described ways of silvering and gilding in a book on alchemy , but this was not done for the purpose of making mirrors. Tin-coated mirrors were first made in Europe in the 15th century. The thin tinfoil used to silver mirrors was known as "tain". When glass mirrors first gained widespread usage in Europe during the 16th century , most were silvered with an amalgam of tin and mercury , In 1835 German chemist Justus von Liebig developed

2035-471: The fragile reflective layer from corrosion, scratches, and other damage. However, the glass layer may absorb some of the light and cause distortions and optical aberrations due to refraction at the front surface, and multiple additional reflections on it, giving rise to "ghost images" (although some optical mirrors such as Mangins take advantage of it). Therefore, precision optical mirrors normally are "front-silvered" or " first-surface ", meaning that

2090-812: The higher-grade ores are reduced in reverberatory furnaces . In 2022, according to the US Geological Survey , China accounted for 54.5% of total antimony production, followed in second place by Russia with 18.2% and Tajikistan with 15.5%. Chinese production of antimony is expected to decline in the future as mines and smelters are closed down by the government as part of pollution control. Especially due to an environmental protection law having gone into effect in January 2015 and revised "Emission Standards of Pollutants for Stanum, Antimony, and Mercury" having gone into effect, hurdles for economic production are higher. Reported production of antimony in China has fallen and

2145-775: The highly unstable gas stibine , SbH 3 : Stibine can also be produced by treating Sb salts with hydride reagents such as sodium borohydride . Stibine decomposes spontaneously at room temperature. Because stibine has a positive heat of formation , it is thermodynamically unstable and thus antimony does not react with hydrogen directly. Organoantimony compounds are typically prepared by alkylation of antimony halides with Grignard reagents . A large variety of compounds are known with both Sb(III) and Sb(V) centers, including mixed chloro-organic derivatives, anions, and cations. Examples include triphenylstibine (Sb(C 6 H 5 ) 3 ) and pentaphenylantimony (Sb(C 6 H 5 ) 5 ). Antimony(III) sulfide , Sb 2 S 3 ,

2200-946: The hydrochloric acid, so this method offers a route to As-free Sb. The pentahalides SbF 5 and SbCl 5 have trigonal bipyramidal molecular geometry in the gas phase, but in the liquid phase, SbF 5 is polymeric , whereas SbCl 5 is monomeric. SbF 5 is a powerful Lewis acid used to make the superacid fluoroantimonic acid ("H 2 SbF 7 "). Oxyhalides are more common for antimony than for arsenic and phosphorus. Antimony trioxide dissolves in concentrated acid to form oxoantimonyl compounds such as SbOCl and (SbO) 2 SO 4 . Compounds in this class generally are described as derivatives of Sb . Antimony forms antimonides with metals, such as indium antimonide (InSb) and silver antimonide ( Ag 3 Sb ). The alkali metal and zinc antimonides, such as Na 3 Sb and Zn 3 Sb 2 , are more reactive. Treating these antimonides with acid produces

2255-455: The largest sailing superyachts; to improve hardness and tensile strength of the lead keel, antimony is mixed with lead between 2% and 5% by volume. Antimony is used in antifriction alloys (such as Babbitt metal ), in bullets and lead shot , electrical cable sheathing, type metal (for example, for linotype printing machines ), solder (some " lead-free " solders contain 5% Sb), in pewter , and in hardening alloys with low tin content in

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2310-432: The low hardness and brittleness of antimony. Antimony has two stable isotopes : Sb with a natural abundance of 57.36% and Sb with a natural abundance of 42.64%. It also has 35 radioisotopes, of which the longest-lived is Sb with a half-life of 2.75 years. In addition, 29 metastable states have been characterized. The most stable of these is Sb with a half-life of 5.76 days. Isotopes that are lighter than

2365-424: The manufacturing of organ pipes . Three other applications consume nearly all the rest of the world's supply. One application is as a stabilizer and catalyst for the production of polyethylene terephthalate . Another is as a fining agent to remove microscopic bubbles in glass, mostly for TV screens – antimony ions interact with oxygen, suppressing the tendency of the latter to form bubbles. The third application

2420-444: The more stable black allotrope. A rare explosive form of antimony can be formed from the electrolysis of antimony trichloride , but it always contains appreciable chlorine and is not really an antimony allotrope. When scratched with a sharp implement, an exothermic reaction occurs and white fumes are given off as metallic antimony forms; when rubbed with a pestle in a mortar, a strong detonation occurs. Elemental antimony adopts

2475-593: The observatory keep a log online of what they have observed. Some things that have been logged are the double star Albireo , the Andromeda Galaxy , a dense patch of stars in the Milky Way near Cygnus , Jupiter with the Galilean moons , the waxing gibbous Moon , Mars , and Alcor and Mizar . Silvering#Aluminum Silvering is the chemical process of coating a non-conductive substrate such as glass with

2530-586: The presence of an externally generated flame, but will extinguish when the external flame is removed. Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. When casting it increases fluidity of the melt and reduces shrinkage during cooling. For most applications involving lead, varying amounts of antimony are used as alloying metal. In lead–acid batteries , this addition improves plate strength and charging characteristics. For sailboats, lead keels are used to provide righting moment, ranging from 600 lbs to over 200 tons for

2585-501: The pure negative as α- ("not"). Edmund Oscar von Lippmann conjectured a hypothetical Greek word ανθήμόνιον anthemonion , which would mean "floret", and cites several examples of related Greek words (but not that one) which describe chemical or biological efflorescence . The early uses of antimonium include the translations, in 1050–1100, by Constantine the African of Arabic medical treatises. Several authorities believe antimonium

2640-447: The reflective layer is on the surface towards the incoming light. The substrate normally provides only physical support, and need not be transparent. A hard, protective, transparent overcoat may be applied to prevent oxidation of the reflective layer and scratching of the metal. Front-coated mirrors achieve reflectivities of 90–95% when new. Ptolemaic Egypt had manufactured small glass mirrors backed by lead , tin, or antimony . In

2695-503: The rigidity of lead-alloy plates in lead–acid batteries . Antimony trioxide is a prominent additive for halogen -containing flame retardants . Antimony is used as a dopant in semiconductor devices . Antimony is a member of group 15 of the periodic table , one of the elements called pnictogens , and has an electronegativity of 2.05. In accordance with periodic trends, it is more electronegative than tin or bismuth , and less electronegative than tellurium or arsenic . Antimony

2750-490: The stable Sb tend to decay by β decay , and those that are heavier tend to decay by β decay , with some exceptions. Antimony is the lightest element to have an isotope with an alpha decay branch, excluding Be and other light nuclides with beta-delayed alpha emission. The abundance of antimony in the Earth's crust is estimated at 0.2 parts per million , comparable to thallium at 0.5 ppm and silver at 0.07 ppm. It

2805-411: The sulfide of antimony. The Egyptians called antimony mśdmt or stm . The Arabic word for the substance, as opposed to the cosmetic, can appear as إثمد ithmid, athmoud, othmod , or uthmod . Littré suggests the first form, which is the earliest, derives from stimmida , an accusative for stimmi . The Greek word στίμμι (stimmi) is used by Attic tragic poets of the 5th century BC, and

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2860-472: Was frequently described in alchemical manuscripts, including the Summa Perfectionis of Pseudo-Geber , written around the 14th century. A description of a procedure for isolating antimony is later given in the 1540 book De la pirotechnia by Vannoccio Biringuccio , predating the more famous 1556 book by Agricola , De re metallica . In this context Agricola has been often incorrectly credited with

2915-462: Was known to German chemist Andreas Libavius in 1615 who obtained it by adding iron to a molten mixture of antimony sulfide, salt and potassium tartrate . This procedure produced antimony with a crystalline or starred surface. With the advent of challenges to phlogiston theory , it was recognized that antimony is an element forming sulfides, oxides, and other compounds, as do other metals. The first discovery of naturally occurring pure antimony in

2970-423: Was later bought from Competition Associates, a racing car company. That scope arrived in 1976, but it was never mounted onto the roof of the GRC due to the aforementioned problems. Instead, it was stored in the basement of Hasbrouck for perhaps 10 years, becoming known as the "Subterranean Telescope". This situation finally led to the 20" being disassembled and the 16" scope being moved to Orchard Hill and installed in

3025-465: Was recognized in predynastic Egypt as an eye cosmetic ( kohl ) as early as about 3100 BC , when the cosmetic palette was invented. An artifact, said to be part of a vase, made of antimony dating to about 3000 BC was found at Telloh , Chaldea (part of present-day Iraq ), and a copper object plated with antimony dating between 2500 BC and 2200 BC has been found in Egypt . Austen, at

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