osmium

{{Main|Isotopes of osmium}}

Osmium has seven naturally occurring isotopes, five of which are stable: {{chem|187|Os}}, {{chem|188|Os}}, {{chem|189|Os}}, {{chem|190|Os}}, and (most abundant) {{chem|192|Os}}. At least 37 artificial radioisotopes and 20 nuclear isomers exist, with mass numbers ranging from 160 to 203; the most stable of these is {{chem|194|Os}} with a half-life of 6 years.{{NUBASE2020}}

{{chem|186|Os}} undergoes alpha decay with such a long half-life {{val|2.0e15|1.1}} years, approximately {{val|140000}} times the age of the universe, that for practical purposes it can be considered stable. {{chem|184|Os}} is also known to undergo alpha decay with a half-life of {{val|1.12e13|0.23}} years. Alpha decay is predicted for all the other naturally occurring isotopes, but this has never been observed, presumably due to very long half-lives. It is predicted that {{chem|184|Os}} and {{chem|192|Os}} can undergo double beta decay, but this radioactivity has not been observed yet.

¹⁸⁹Os has a spin of 5/2 but ¹⁸⁷Os has a nuclear spin 1/2. Its low natural abundance (1.64%) and low nuclear magnetic moment means that it is one of the most difficult natural abundance isotopes for NMR spectroscopy.{{cite journal|doi=10.1021/om960053i |title=¹⁸⁷Os NMR Study of (η⁶-Arene)osmium(II) Complexes: Separation of Electronic and Steric Ligand Effects |date=1996 |last1=Bell |first1=Andrew G. |last2=Koźmiński |first2=Wiktor |last3=Linden |first3=Anthony |last4=von Philipsborn |first4=Wolfgang |journal=Organometallics |volume=15 |issue=14 |pages=3124–3135 }}

{{chem|187|Os}} is the descendant of {{chem|187|Re}} (half-life {{val|4.56|e=10|u=years}}) and is used extensively in dating terrestrial as well as meteoric rocks (see Rhenium–osmium dating). It has also been used to measure the intensity of continental weathering over geologic time and to fix minimum ages for stabilization of the mantle roots of continental cratons. This decay is a reason why rhenium-rich minerals are abnormally rich in {{chem|187|Os}}.{{cite journal|first=Józef|last=Dąbek|author2=Halas, Stanislaw|title=Physical Foundations of Rhenium-Osmium Method – A Review|journal=Geochronometria|volume=27|date=2007|issue=1 |doi=10.2478/v10003-007-0011-4|pages=23–26|bibcode=2007Gchrm..27...23D |doi-access=free}} However, the most notable application of osmium isotopes in geology has been in conjunction with the abundance of iridium, to characterise the layer of shocked quartz along the Cretaceous–Paleogene boundary that marks the extinction of the non-avian dinosaurs 65 million years ago.{{cite journal|title=Extraterrestrial cause for the Cretaceous–Tertiary extinction|author=Alvarez, L. W.|author-link=Luis Walter Alvarez|author2=Alvarez, W.|author3=Asaro, F.|author4=Michel, H. V.|date=1980|journal=Science|volume=208|issue=4448|pages=1095–1108|doi=10.1126/science.208.4448.1095|pmid=17783054|bibcode=1980Sci...208.1095A|url=http://earthscience.rice.edu/wp-content/uploads/2015/11/Alvarez_K-Timpact_Science80.pdf|citeseerx=10.1.1.126.8496|s2cid=16017767|access-date=November 2, 2017|archive-date=May 21, 2023|archive-url=https://web.archive.org/web/20230521231012/https://earthscience.rice.edu/wp-content/uploads/2015/11/Alvarez_K-Timpact_Science80.pdf|url-status=live}}

Osmium was discovered in 1803 by Smithson Tennant and William Hyde Wollaston in London, England.{{cite journal|title=Osmium|journal=Metallurgist|volume=18|issue= 2|date=1974|doi=10.1007/BF01132596|pages=155–157|first=S. I.|last=Venetskii|s2cid=241230590 }} The discovery of osmium is intertwined with that of platinum and the other metals of the platinum group. Platinum reached Europe as platina ("small silver"), first encountered in the late 17th century in silver mines around the Chocó Department, in Colombia.{{cite journal|title=The Platinum of New Granada: Mining and Metallurgy in the Spanish Colonial Empire|author=McDonald, M.|journal=Platinum Metals Review|volume=3|issue=4|date=959|pages=140–145|doi=10.1595/003214059X34140145 |url=http://www.platinummetalsreview.com/dynamic/article/view/pmr-v3-i4-140-145|access-date=October 15, 2008|archive-url=https://web.archive.org/web/20110609195507/http://www.platinummetalsreview.com/dynamic/article/view/pmr-v3-i4-140-145|archive-date=June 9, 2011|url-status=dead|url-access=subscription}} The discovery that this metal was not an alloy, but a distinct new element, was published in 1748.{{cite book|author=Juan, J.|author2=de Ulloa, A.|date=1748|title=Relación histórica del viage a la América Meridional|volume=1|page=606|language=es}}

Chemists who studied platinum dissolved it in aqua regia (a mixture of hydrochloric and nitric acids) to create soluble salts. They always observed a small amount of a dark, insoluble residue. Joseph Louis Proust thought that the residue was graphite.{{cite journal|title=A History of Iridium|first=L. B.|last=Hunt|journal=Platinum Metals Review|volume=31|issue=1|date=1987|url=http://www.platinummetalsreview.com/pdf/pmr-v31-i1-032-041.pdf|access-date=2012-03-15|pages=32–41|doi=10.1595/003214087X3113241 |archive-date=March 4, 2012|archive-url=https://web.archive.org/web/20120304225507/http://www.platinummetalsreview.com/pdf/pmr-v31-i1-032-041.pdf|url-status=dead}} Victor Collet-Descotils, Antoine François, comte de Fourcroy, and Louis Nicolas Vauquelin also observed iridium in the black platinum residue in 1803, but did not obtain enough material for further experiments. Later the two French chemists Fourcroy and Vauquelin identified a metal in a platinum residue they called ptène.{{Cite journal|last1=Haubrichs|first1=Rolf|last2=Zaffalon|first2=Pierre-Leonard|date=2017|title=Osmium vs. 'Ptène': The Naming of the Densest Metal|journal=Johnson Matthey Technology Review|volume=61|issue=3|pages=190|doi=10.1595/205651317x695631|doi-access=free}}

In 1803, Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids and obtained a volatile new oxide, which he believed was of this new metal—which he named ptene, from the Greek word {{lang|el|πτηνος}} (ptènos) for winged.{{cite journal|doi=10.1595/147106704X4844|title=Bicentenary of Four Platinum Group Metals. Part II: Osmium and iridium – events surrounding their discoveries|author=Griffith, W. P.|journal=Platinum Metals Review|volume=48|issue=4|date=2004|pages=182–189|doi-access=free}}{{cite book|title=A System of Chemistry of Inorganic Bodies|url=https://archive.org/details/asystemchemistr08thomgoog|author=Thomson, T.|author-link=Thomas Thomson (chemist)|publisher=Baldwin & Cradock, London; and William Blackwood, Edinburgh|date=1831|page=[https://archive.org/details/asystemchemistr08thomgoog/page/n726 693]}} However, Tennant, who had the advantage of a much larger amount of residue, continued his research and identified two previously undiscovered elements in the black residue, iridium and osmium. He obtained a yellow solution (probably of cis–[Os(OH)₂O₄]²⁻) by reactions with sodium hydroxide at red heat. After acidification he was able to distill the formed OsO₄. He named it osmium after Greek osme meaning "a smell", because of the chlorine-like and slightly garlic-like smell of the volatile osmium tetroxide.{{cite book|title=Discovery of the Elements|url=https://archive.org/details/discoveryofeleme0000week|url-access=registration|pages=[https://archive.org/details/discoveryofeleme0000week/page/414 414–418]|author=Weeks, M. E.|date= 1968|edition=7|publisher=Journal of Chemical Education|isbn=978-0-8486-8579-9|oclc=23991202}} Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804.{{cite journal|title=On Two Metals, Found in the Black Powder Remaining after the Solution of Platina|first=S.|last=Tennant|journal=Philosophical Transactions of the Royal Society|volume=94|date=1804|pages=411–418|jstor=107152|doi=10.1098/rstl.1804.0018|url=https://zenodo.org/record/1432312|doi-access=free|access-date=August 27, 2019|archive-date=May 28, 2023|archive-url=https://web.archive.org/web/20230528180903/https://zenodo.org/record/1432312|url-status=live}}

Uranium and osmium were early successful catalysts in the Haber process, the nitrogen fixation reaction of nitrogen and hydrogen to produce ammonia, giving enough yield to make the process economically successful. At the time, a group at BASF led by Carl Bosch bought most of the world's supply of osmium to use as a catalyst. Shortly thereafter, in 1908, cheaper catalysts based on iron and iron oxides were introduced by the same group for the first pilot plants, removing the need for the expensive and rare osmium.{{cite book| last = Smil| first = Vaclav| title = Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production| url = https://books.google.com/books?id=G9FljcEASycC| date = 2004| publisher = MIT Press| isbn = 978-0-262-69313-4| pages = 80–86 }}

Osmium is now obtained primarily from the processing of platinum and nickel ores.{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf|publisher=United States Geological Survey USGS|access-date=2008-09-16|title=2006 Minerals Yearbook: Platinum-Group Metals|first=Micheal W.|last=George|archive-date=January 11, 2019|archive-url=https://web.archive.org/web/20190111062032/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf|url-status=live}}

File:Platinum nuggets.jpg metals]]

Osmium is one of the least abundant stable elements in Earth's crust, with an average mass fraction of 50 parts per trillion in the continental crust.{{cite journal|doi=10.1016/0016-7037(95)00038-2|pages=1217–1232|title=The composition of the continental crust|date=1995|issue=7|author=Wedepohl, Hans K|journal=Geochimica et Cosmochimica Acta|volume=59|bibcode=1995GeCoA..59.1217W|url=https://doi.pangaea.de/10.1594/PANGAEA.841674|access-date=August 27, 2019|archive-date=November 3, 2023|archive-url=https://web.archive.org/web/20231103024424/https://doi.pangaea.de/10.1594/PANGAEA.841674|url-status=live|url-access=subscription}}

Osmium is found in nature as an uncombined element or in natural alloys; especially the iridium–osmium alloys, osmiridium (iridium rich), and iridosmium (osmium rich).{{cite book| last = Emsley| first = J.| title = Nature's Building Blocks: An A-Z Guide to the Elements| date = 2003| publisher = Oxford University Press| location = Oxford, England, UK| isbn = 978-0-19-850340-8| pages = [https://archive.org/details/naturesbuildingb0000emsl/page/199 199–201]| chapter = Osmium| chapter-url = https://archive.org/details/naturesbuildingb0000emsl/page/199}} In nickel and copper deposits, the platinum-group metals occur as sulfides (i.e., {{chem2|(Pt,Pd)S}}), tellurides (e.g., {{chem2|PtBiTe}}), antimonides (e.g., {{chem2|PdSb}}), and arsenides (e.g., {{chem2|PtAs2}}); in all these compounds platinum is exchanged by a small amount of iridium and osmium. As with all of the platinum-group metals, osmium can be found naturally in alloys with nickel or copper.{{cite journal|doi=10.1016/j.mineng.2004.04.001|journal=Minerals Engineering|volume=17|issue=9–10|date=2004|pages=961–979|title=Characterizing and recovering the platinum group minerals—a review|first=Z.|last=Xiao|author2=Laplante, A. R.|bibcode=2004MiEng..17..961X }}

Within Earth's crust, osmium, like iridium, is found at highest concentrations in three types of geologic structure: igneous deposits (crustal intrusions from below), impact craters, and deposits reworked from one of the former structures. The largest known primary reserves are in the Bushveld Igneous Complex in South Africa,{{cite book |title=Kirk Othmer Encyclopedia of Chemical Technology |first = R. J.|last=Seymour|author2=O'Farrelly, J. I. |chapter=Platinum-group metals|doi=10.1002/0471238961.1612012019052513.a01.pub2|date=2001|publisher=Wiley|isbn = 978-0471238966}} though the large copper–nickel deposits near Norilsk in Russia, and the Sudbury Basin in Canada are also significant sources of osmium. Smaller reserves can be found in the United States. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia, are still a source for platinum-group metals. The second large alluvial deposit was found in the Ural Mountains, Russia, which is still mined.{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf|publisher=United States Geological Survey USGS|access-date=2008-09-16|title=Commodity Report: Platinum-Group Metals|archive-date=January 11, 2019|archive-url=https://web.archive.org/web/20190111015125/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf|url-status=live}}

File:Osmium cluster.jpgs, grown by chemical vapor transport]]

Osmium is obtained commercially as a by-product from nickel and copper mining and processing. During electrorefining of copper and nickel, noble metals such as silver, gold and the platinum-group metals, together with non-metallic elements such as selenium and tellurium, settle to the bottom of the cell as anode mud, which forms the starting material for their extraction.{{cite journal|author=George, M. W.|title=Platinum-group metals|journal=U.S. Geological Survey Mineral Commodity Summaries|date=2008|url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf|access-date=September 16, 2008|archive-date=January 11, 2019|archive-url=https://web.archive.org/web/20190111015125/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf|url-status=live}}{{cite book|url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf|publisher=United States Geological Survey USGS|access-date=2008-09-16|title=2006 Minerals Yearbook: Platinum-Group Metals|first=M. W.|last=George|archive-date=January 11, 2019|archive-url=https://web.archive.org/web/20190111062032/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf|url-status=live}} Separating the metals requires that they first be brought into solution. Several methods can achieve this, depending on the separation process and the composition of the mixture. Two representative methods are fusion with sodium peroxide followed by dissolution in aqua regia, and dissolution in a mixture of chlorine with hydrochloric acid.{{cite book |author=Renner, H. |display-authors=4 |author2=Schlamp, G. |author3=Kleinwächter, I. |author4=Drost, E. |author5=Lüschow, H. M. |author6=Tews, P. |author7=Panster, P. |author8=Diehl, M. |author9=Lang, J. |author10=Kreuzer, T. |author11=Knödler, A. |author12=Starz, K. A. |author13=Dermann, K. |author14=Rothaut, J. |author15=Drieselman, R.|chapter=Platinum group metals and compounds|title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley|date=2002|doi=10.1002/14356007.a21_075|isbn=978-3527306732 }} Osmium, ruthenium, rhodium, and iridium can be separated from platinum, gold, and base metals by their insolubility in aqua regia, leaving a solid residue. Rhodium can be separated from the residue by treatment with molten sodium bisulfate. The insoluble residue, containing ruthenium, osmium, and iridium, is treated with sodium oxide, in which Ir is insoluble, producing water-soluble ruthenium and osmium salts. After oxidation to the volatile oxides, {{chem|RuO|4}} is separated from {{chem|OsO|4}} by precipitation of (NH₄)₃RuCl₆ with ammonium chloride.

After it is dissolved, osmium is separated from the other platinum-group metals by distillation or extraction with organic solvents of the volatile osmium tetroxide.{{cite journal|title=The Platinum Metals|first=Raleigh|last=Gilchrist|journal=Chemical Reviews|date=1943|volume=32|issue=3|pages=277–372|doi=10.1021/cr60103a002|s2cid=96640406 }} The first method is similar to the procedure used by Tennant and Wollaston. Both methods are suitable for industrial-scale production. In either case, the product is reduced using hydrogen, yielding the metal as a powder or sponge that can be treated using powder metallurgy techniques.{{cite journal|first=L. B.|last=Hunt|author2=Lever, F. M.|journal=Platinum Metals Review|volume=13|issue=4|date=1969|pages=126–138|title=Platinum Metals: A Survey of Productive Resources to industrial Uses|doi=10.1595/003214069X134126138 |url=http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf|access-date=2008-10-02|archive-date=October 29, 2008|archive-url=https://web.archive.org/web/20081029205825/http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf|url-status=dead}}

Estimates of annual worldwide osmium production are on the order of several hundred to a few thousand kilograms.{{cite journal |last1=Girolami |first1=Gregory |title=Osmium weighs in |journal=Nature Chemistry |date=November 2012 |volume=4 |issue=11 |pages=954 |doi=10.1038/nchem.1479|doi-access=free |pmid=23089872 |bibcode=2012NatCh...4..954G }} Production and consumption figures for osmium are not well reported because demand for the metal is limited and can be fulfilled with the byproducts of other refining processes. To reflect this, statistics often report osmium with other minor platinum group metals such as iridium and ruthenium. US imports of osmium from 2014 to 2021 averaged 155 kg annually.{{cite web |author1=Singerling, S.A. |author2=Schulte, R.F. |title=2018 Minerals Yearbook: Platinum-Group Metals [Advance Release] |url=https://www.usgs.gov/centers/national-minerals-information-center/platinum-group-metals-statistics-and-information |website=Platinum-Group Metals Statistics and Information |publisher=U.S. Geological Survey |archive-url=https://web.archive.org/web/20230714121323/https://www.usgs.gov/centers/national-minerals-information-center/platinum-group-metals-statistics-and-information |archive-date=July 14, 2023 |date=August 2021 |access-date=September 24, 2023 |url-status=bot: unknown }}{{cite web |last1=Schulte |first1=R.F. |title=Mineral commodity summaries 2022 - Platinum-Group Metals |url=https://www.usgs.gov/centers/national-minerals-information-center/platinum-group-metals-statistics-and-information |website=Platinum-Group Metals Statistics and Information |publisher=U.S. Geological Survey |archive-url=https://web.archive.org/web/20230714121323/https://www.usgs.gov/centers/national-minerals-information-center/platinum-group-metals-statistics-and-information |archive-date=July 14, 2023 |access-date=September 24, 2023 |url-status=bot: unknown }}

Because osmium is virtually unforgeable when fully dense and very fragile when sintered, it is rarely used in its pure state, but is instead often alloyed with other metals for high-wear applications. Osmium alloys such as osmiridium are very hard and, along with other platinum-group metals, are used in the tips of fountain pens, instrument pivots, and electrical contacts, as they can resist wear from frequent operation. They were also used for the tips of phonograph styli during the late 78 rpm and early "LP" and "45" record era, circa 1945 to 1955. Osmium-alloy tips were significantly more durable than steel and chromium needle points, but wore out far more rapidly than competing, and costlier, sapphire and diamond tips, so they were discontinued.{{cite book| author = Cramer, Stephen D. | author2 = Covino, Bernard S. Jr.| name-list-style = amp| title = ASM Handbook Volume 13B. Corrosion: Materials| url = https://books.google.com/books?id=wGdFAAAAYAAJ| date = 2005| publisher = ASM International| isbn = 978-0-87170-707-9 }}

Osmium tetroxide has been used in fingerprint detection{{cite journal|title=The Use of Hydrogen Fluoride in the Development of Latent Fingerprints Found on Glass Surfaces|first=Herbert L.|last=MacDonell|journal=The Journal of Criminal Law, Criminology, and Police Science|volume=51|issue=4|date=1960|pages=465–470|jstor=1140672|doi=10.2307/1140672|url=https://scholarlycommons.law.northwestern.edu/cgi/viewcontent.cgi?article=4971&context=jclc|access-date=December 2, 2018|archive-date=September 28, 2023|archive-url=https://web.archive.org/web/20230928161103/https://scholarlycommons.law.northwestern.edu/cgi/viewcontent.cgi?article=4971&context=jclc|url-status=live|url-access=subscription}} and in staining fatty tissue for optical and electron microscopy. As a strong oxidant, it cross-links lipids mainly by reacting with unsaturated carbon–carbon bonds and thereby both fixes biological membranes in place in tissue samples and simultaneously stains them. Because osmium atoms are extremely electron-dense, osmium staining greatly enhances image contrast in transmission electron microscopy (TEM) studies of biological materials. Those carbon materials otherwise have very weak TEM contrast.{{cite book| author2 = Russell, Lonnie D.| last = Bozzola| first = John J.| title = Electron microscopy : principles and techniques for biologists| chapter-url = https://books.google.com/books?id=zMkBAPACbEkC&pg=PA21| date = 1999| publisher = Jones and Bartlett| location = Sudbury, Mass.| isbn = 978-0-7637-0192-5| pages = 21–31| chapter = Specimen Preparation for Transmission Electron Microscopy }} Another osmium compound, osmium ferricyanide (OsFeCN), exhibits similar fixing and staining action.{{cite book| author = Chadwick, D.| title = Role of the sarcoplasmic reticulum in smooth muscle| date = 2002| publisher = John Wiley and Sons| isbn = 978-0-470-84479-3| pages = [https://archive.org/details/roleofsarcoplasm0000unse/page/259 259–264]| url-access = registration| url = https://archive.org/details/roleofsarcoplasm0000unse/page/259}}

The tetroxide and its derivative potassium osmate are important oxidants in organic synthesis. For the Sharpless asymmetric dihydroxylation, which uses osmate for the conversion of a double bond into a vicinal diol, Karl Barry Sharpless was awarded the Nobel Prize in Chemistry in 2001.{{cite journal|last=Kolb|first=H. C.|author2=Van Nieuwenhze, M. S.|author3=Sharpless, K. B.|journal=Chemical Reviews|date=1994|volume=94|issue=8|pages=2483–2547|doi=10.1021/cr00032a009|title=Catalytic Asymmetric Dihydroxylation}}{{cite journal|title=2001 Nobel Prize in Chemistry|last=Colacot|first=T. J.|journal=Platinum Metals Review|volume=46|issue=2|date=2002|pages=82–83|doi=10.1595/003214002X4628283 |url=http://www.platinummetalsreview.com/pdf/pmr-v46-i2-082-083.pdf|access-date=June 12, 2009|archive-date=January 31, 2013|archive-url=https://web.archive.org/web/20130131104016/http://www.platinummetalsreview.com/pdf/pmr-v46-i2-082-083.pdf|url-status=dead}} OsO₄ is very expensive for this use, so KMnO₄ is often used instead, even though the yields are less for this cheaper chemical reagent.

In 1898, the Austrian chemist Auer von Welsbach developed the Oslamp with a filament made of osmium, which he introduced commercially in 1902. After only a few years, osmium was replaced by tungsten, which is more abundant (and thus cheaper) and more stable. Tungsten has the highest melting point among all metals, and its use in light bulbs increases the luminous efficacy and life of incandescent lamps.

The light bulb manufacturer Osram (founded in 1906, when three German companies, Auer-Gesellschaft, AEG and Siemens & Halske, combined their lamp production facilities) derived its name from the elements of osmium and Wolfram (the latter is German for tungsten).{{cite journal|title=Scanning our past from London: the filament lamp and new materials|first=B.|journal=Proceedings of the IEEE|date=2001|volume=89|issue=3|pages=413–415|doi=10.1109/5.915382|last=Bowers, B.|s2cid=28155048}}

Like palladium, powdered osmium effectively absorbs hydrogen atoms. This could make osmium a potential candidate for a metal-hydride battery electrode. However, osmium is expensive and would react with potassium hydroxide, the most common battery electrolyte.{{cite journal|title=The Solubility of Hydrogen in the Platinum Metals under High Pressure|first=V. E.|last=Antonov|author2=Belash, I. T.|author3=Malyshev, V. Yu.|author4=Ponyatovsky, E. G.|journal=Platinum Metals Review|volume=28|issue=4|date=1984|pages=158–163|doi=10.1595/003214084X284158163 |url=http://www.platinummetalsreview.com/pdf/pmr-v28-i4-158-163.pdf|access-date=June 4, 2009|archive-date=January 31, 2013|archive-url=https://web.archive.org/web/20130131165432/http://www.platinummetalsreview.com/pdf/pmr-v28-i4-158-163.pdf|url-status=dead}}

Osmium has high reflectivity in the ultraviolet range of the electromagnetic spectrum; for example, at 600 Å osmium has a reflectivity twice that of gold.{{cite journal|doi=10.1364/AO.24.002959|title=Osmium coated diffraction grating in the Space Shuttle environment: performance|date=1985|author=Torr, Marsha R.|journal=Applied Optics|volume=24|page=2959|pmid=18223987|issue=18|bibcode=1985ApOpt..24.2959T }} This high reflectivity is desirable in space-based UV spectrometers, which have reduced mirror sizes due to space limitations. Osmium-coated mirrors were flown in several space missions aboard the Space Shuttle, but it soon became clear that the oxygen radicals in low Earth orbit are abundant enough to significantly deteriorate the osmium layer.{{cite journal|doi=10.1364/AO.24.002660|title=Low earth orbit environmental effects on osmium and related optical thin-film coatings|date=1985|author=Gull, T. R.|journal=Applied Optics|volume=24|page=2660|pmid=18223936|last2=Herzig|first2=H.|last3=Osantowski|first3=J. F.|last4=Toft|first4=A. R.|issue=16|bibcode=1985ApOpt..24.2660G }}

File:Sharpless Dihydroxylation Scheme.png|The Sharpless dihydroxylation:
R_L = largest substituent; R_M = medium-sized substituent; R_S = smallest substituent

File:NASAmirroroxidation.jpg|Post-flight appearance of Os, Ag, and Au mirrors from the front (left images) and rear panels of the Space Shuttle. Blackening reveals oxidation due to irradiation by oxygen atoms.{{cite web|publisher=NASA|last1=Linton|first1=Roger C.|last2=Kamenetzky|first2=Rachel R.|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930019094_1993019094.pdf|title=Second LDEF post-retrieval symposium interim results of experiment A0034|access-date=2009-06-06|year=1992|archive-date=November 4, 2023|archive-url=https://web.archive.org/web/20231104100732/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930019094_1993019094.pdf|url-status=live}}{{cite journal|title=LDEF experiment A0034: Atomic oxygen stimulated outgassing|bibcode=1992ldef.symp..763L|last1=Linton|first1=Roger C.|last2=Kamenetzky|first2=Rachel R.|last3=Reynolds|first3=John M.|last4=Burris|first4=Charles L.|date=1992|page=763|journal=NASA Langley Research Center}}

File:Osmium-2.jpg|A bead of osmium, about 0.5 cm in diameter, displaying the metal's reflectivity

The primary hazard presented by metallic osmium is the potential formation of osmium tetroxide (OsO₄), which is volatile and very poisonous.{{cite book |last1=Lebeau |first1=Alex |title=Hamilton & Hardy's Industrial Toxicology |date=20 March 2015 |publisher=John Wiley & Sons, Inc. |isbn=978-1-118-83401-5 |pages=187–192 |language=en |chapter=Platinum Group Elements: Palladium, Iridium, Osmium, Rhodium, and Ruthenium}} This reaction is thermodynamically favorable at room temperature,{{cite web |title=Osmium(VIII) oxide |url=https://hbcp.chemnetbase.com/ |website=CRC Handbook of Chemistry and Physics, 103rd Edition (Internet Version 2022) |publisher=CRC Press/Taylor & Francis Group |access-date=6 February 2023 |archive-date=October 28, 2023 |archive-url=https://web.archive.org/web/20231028215703/https://hbcp.chemnetbase.com/contents/ContentsSearch.xhtml?dswid=7699 |url-status=live }} but the rate depends on temperature and the surface area of the metal.{{cite journal |last1=McLaughlin |first1=A. I. G. |last2=Milton |first2=R. |last3=Perry |first3=Kenneth M. A. |title=Toxic Manifestations of Osmium Tetroxide |journal=Occupational and Environmental Medicine |date=1 July 1946 |volume=3 |issue=3 |pages=183–186 |doi=10.1136/oem.3.3.183|pmid=20991177 |pmc=1035752 }}{{cite journal |last1=Friedova |first1=Natalie |last2=Pelclova |first2=Daniela |last3=Obertova |first3=Nikola |last4=Lach |first4=Karel |last5=Kesslerova |first5=Katerina |last6=Kohout |first6=Pavel |title=Osmium absorption after osmium tetroxide skin and eye exposure |journal=Basic & Clinical Pharmacology & Toxicology |date=November 2020 |volume=127 |issue=5 |pages=429–433 |doi=10.1111/bcpt.13450|pmid=32524772 |s2cid=219588237 }} As a result, bulk material is not considered hazardous{{cite book |title=Sax's Dangerous Properties of Industrial Materials |date=15 October 2012 |publisher=John Wiley & Sons, Inc. |isbn=978-0-471-70134-7 |url=https://doi.org/10.1002/0471701343.sdp45229 |access-date=5 February 2023 |language=en |chapter=Osmium 7440-04-2|pages=1–2 |doi=10.1002/0471701343.sdp45229 }}{{cite journal |last1=Luttrell |first1=William E. |last2=Giles |first2=Cory B. |title=Toxic tips: Osmium tetroxide |journal=Journal of Chemical Health & Safety |date=1 September 2007 |volume=14 |issue=5 |pages=40–41 |doi=10.1016/j.jchas.2007.07.003}}{{cite journal |last1=Smith |first1=Ivan C. |last2=Carson |first2=Bonnie L. |last3=Ferguson |first3=Thomas L. |title=Osmium: An Appraisal of Environmental Exposure |journal=Environmental Health Perspectives |date=August 1974 |volume=8 |pages=201–213 |doi=10.1289/ehp.748201 |pmid=4470919 |pmc=1474945 |bibcode=1974EnvHP...8..201S |url=https://doi.org/10.1289/ehp.748201 |language=en |issn=0091-6765}} while powders react quickly enough that samples can sometimes smell like OsO₄ if they are handled in air.{{cite web |last1=Gadaskina |first1=I. D. |title=Osmium |url=https://www.iloencyclopaedia.org/part-ix-21851/metals-chemical-properties-and-toxicity/item/178-osmium |website=ILO Encyclopaedia of Occupational Health and Safety |access-date=6 February 2023 |language=en-gb |archive-date=November 3, 2023 |archive-url=https://web.archive.org/web/20231103014706/https://www.iloencyclopaedia.org/part-ix-21851/metals-chemical-properties-and-toxicity/item/178-osmium |url-status=live }}

Between 1990 and 2010, the nominal price of osmium metal was almost constant, while inflation reduced the real value from ~US{{convert|950|$/ozt|$/kg}} to ~US{{convert|600|$/ozt|$/kg}}{{cite web |title=USGS Scientific Investigations Report 2012–5188: Metal Prices in the United States Through 2010 |url=http://pubs.usgs.gov/sir/2012/5188 |website=pubs.usgs.gov |publisher=U.S. Geological Survey |access-date=11 July 2023 |pages=119–128 |date=2013 |archive-date=November 7, 2023 |archive-url=https://web.archive.org/web/20231107214738/https://pubs.usgs.gov/sir/2012/5188/ |url-status=live }} Because osmium has few commercial applications, it is not heavily traded and prices are seldom reported.

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{{reflist|30em}}

• {{cite book |editor-last=Haynes |editor-first=William M. |year=2011 |title=CRC Handbook of Chemistry and Physics |title-link=CRC Handbook of Chemistry and Physics |edition=92nd |publisher=CRC Press |isbn=978-1439855119}}

{{Commons|Osmium}}

{{Wiktionary|osmium}}

• [http://www.periodicvideos.com/videos/076.htm Osmium] {{Webarchive|url=https://web.archive.org/web/20130322195133/http://periodicvideos.com/videos/076.htm |date=March 22, 2013 }} at The Periodic Table of Videos (University of Nottingham)
• Flegenheimer, J. (2014). [https://web.archive.org/web/20150619170958/http://www.uff.br/RVQ/index.php/rvq/article/viewFile/660/450 "The Mystery of the Disappearing Isotope"] (via the Wayback Machine). Revista Virtual de Química. V. XX.
• {{cite EB1911|wstitle=Osmium|volume=20|page=352}}

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{{Osmium compounds}}

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