# Leonite > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Leonite > Markdown URL: https://mediated.wiki/source/Leonite.md > Source: https://en.wikipedia.org/wiki/Leonite > Source revision: 1320255284 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Hydrated double sulfate of magnesium and potassium}} {{Infobox mineral | name = Leonite | image = Leonite-Halite-112539.jpg | alt = leonite as white pseudomorphs after sharp freestanding picromerite crystals sizes to 2 cm, perched on a matrix of crystallized halite. 5.5 × 4.7 × 3.4 cm | caption = Leonite | category = [Sulfate mineral](/source/Sulfate_mineral) | formula = K2Mg(SO4)2·4H2O | IMAsymbol = Leo{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}} | molweight = 366.69 g/mol | strunz = 7.CC.55 | dana = 29.03.03.01 | system = [Monoclinic](/source/Monoclinic) | class = Prismatic (2/m)
(same [H-M symbol](/source/H-M_symbol)) | symmetry = ''C2/m'' | unit cell = a = 11.78, b = 9.53
c = 9.88 [Å]; β = 95.4°; Z = 4 | color = White to colorless, yellow | colour = | habit = Tabular crystals | twinning = {100} | cleavage = none | fracture = conchoidal | tenacity = | mohs = 2.5–3 | luster = Vitreous or waxy | streak = White | diaphaneity = Transparent to translucent | gravity = 2.201 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.479 nβ = 1.482 nγ = 1.487 | birefringence = δ = 0.008 | pleochroism = | 2V = Measured: 90° Calc: 76° | dispersion = none | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = easy | diagnostic = | solubility = | impurities = | alteration = | other = Leonit, 钾镁矾, Leonita, Леонит, Kalium-Astrakanit, Kalium-Blödit | references = [http://www.mindat.org/min-2377.html Mindat.org][http://www.webmineral.com/data/Leonite.shtml Leonite Webmineral data] }} '''Leonite''' is a hydrated double [sulfate](/source/sulfate) of [magnesium](/source/magnesium) and [potassium](/source/potassium). It has the formula K2SO4·MgSO4·4H2O. The mineral was named after Leo Strippelmann, who was director of the salt works at [Westeregeln](/source/Westeregeln) in Germany.{{cite web|title=Leonite|url=http://rruff.info/doclib/hom/leonite.pdf|publisher=Mineral Data Publishing|date=2005}} The mineral is part of the [blodite group](/source/blodite_group) of hydrated double sulfate minerals. ==Properties== Leonite has a bitter taste.{{cite journal|last1=Bilonizhka|first1=P.|title=Leonite in Pre-Carpathian Evaporites and its Transformation Under Increased Temperatures|journal=Acta Mineralogica-Petrographica|date=2003|volume=1|page=14|url=http://www.mineral.hermuz.hu/act_03/pdf/014.pdf|access-date=17 November 2015|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304051656/http://www.mineral.hermuz.hu/act_03/pdf/014.pdf|url-status=dead}} When leonite is analyzed for elements, it is usually contaminated with sodium and chloride ions, as it commonly occurs with sodium chloride. thumb|Leonite white pseudomorphs after picromerite crystals from Potash Mine, Roßleben, Querfurt, Saxony-Anhalt. thumb|Leonite from Wintershall Potash Works, Heringen, Werra Valley, North Hesse. ===Crystal structure=== In the mineral family of leonite, the [lattice](/source/Crystal_structure) contains sulfate tetrahedrons, a divalent element in an [octahedral](/source/Octahedral_molecular_geometry) position surrounded by [oxygen](/source/oxygen), and water and univalent metal (potassium) linking these other components together. One sulfate group is [disordered](/source/Order_and_disorder_(physics)) at [room temperature](/source/room_temperature). The disordered sulfate becomes fixed in position as temperature is lowered. The crystal form also changes at lower temperatures, so two other crystalline forms of leonite exist at lower temperatures. The divalent metal cation (magnesium) is embedded in oxygen octahedra, four from water around the equator, and two from sulfate ions at the opposite poles. In the crystal there are two different octahedral environments. Each of these octahedra are joined together by potassium ions and hydrogen bonds.{{cite journal|last1=Hertweck|first1=Birgit|last2=Libowitzky|first2=Eugen|title=Vibrational spectroscopy of phase transitions in leonite-type minerals|journal=European Journal of Mineralogy|date=1 December 2002|volume=14|issue=6|pages=1009–1017|doi=10.1127/0935-1221/2002/0014-1009|bibcode=2002EJMin..14.1009H}} ===Phase changes=== The sulfate occurs in layers parallel to the [(001)](/source/Miller_index) surface. In the room temperature form, the sequence is ODODODODOD with O=ordered, and D=disordered. In the next form at lower temperatures, the disordered sulfate appears in two different orientations giving the sequence OAOBOAOBOAOBOAOB. At the lowest temperatures, the sequence simplifies to OAOAOAOAOAO.{{cite journal|last1=Libowitzky|first1=Eugen|title=Crystal Structure Dynamics: Evidence by Diffraction and Spectroscopy|url=http://hrcak.srce.hr/file/6807|journal=Croatica Chemica Acta|volume=29|issue=2|date=2006|pages=299–309}} The first [phase transition](/source/phase_transition) happens at −4 °C.{{cite journal|last1=Hertweck|first1=B.|last2=Armbruster|first2=T.|last3=Libowitzky|first3=E.|title=Multiple phase transitions of leonite-type compounds: optical, calorimetric, and X-ray data|journal=Mineralogy and Petrology|date=1 July 2002|volume=75|issue=3–4|pages=245–259|doi=10.1007/s007100200027|bibcode=2002MinPe..75..245H|s2cid=97758100}} At {{convert|170|K|C}}, the crystals have space group I2/a, lattice parameters a = 11.780 Å, b = 9.486 Å, c = 19.730 Å, β = 95.23°, 8 formula per unit cell, and a cell volume of V = 2195.6 Å3. The c dimension and unit cell volume are doubled due to the presence of four sulfate layers rather than two as in the other forms. The next phase change happens at −153 °C. At {{convert|100|K|C}}, the space group is P21/a, a = 11.778 Å, b = 9.469 Å, c = 9.851 Å, β = 95.26°, 4 formula per unit cell, and a cell volume of V = 1094.01 Å3.{{cite journal|last1=Hertweck|first1=Birgit|last2=Giester|first2=Gerald|last3=Libowitzky|first3=Eugen|title=The crystal structures of the low-temperature phases of leonite-type compounds, K2 Me(SO4)2 ·4H2O (Me = Mg, Mn, Fe)|journal=American Mineralogist|date=October 2001|volume=86|issue=10|pages=1282–1292|doi=10.2138/am-2001-1016|bibcode=2001AmMin..86.1282H|s2cid=99328013}} ===Temperature effects=== As temperature increases, the cell volume gradually increases for the I2/a and C2/m phases; however, the a dimension decreases with increasing temperature. The change in a dimension is −11×10−6 K−1. [Birefringence](/source/Birefringence) drops as temperature rises. It varies from 0.0076 at −150 °C down to 0.0067 at 0 °C and 0.0061 at 100 °C. At the lower phase transition, birefringence steps down as the temperature drops; for the upper phase transition, it is continuous but not constant. At the upper phase transition, −4 °C, latent heat is released, and the heat capacity changes. This transition has a fair bit of hysteresis. At the lower phase transition, heat capacity stays the same, but latent heat is released. Leonite starts to lose water at 130 °C, but only really breaks down at 200 °C: :K2Mg(SO4)2·4H2O(s) → K2Mg(SO4)2·2H2O(s) + 2H2O(g). At even higher temperatures, [langbeinite](/source/langbeinite) and arcanite (anhydrous [potassium sulfate](/source/potassium_sulfate)) and steam are all that remain:{{cite journal|last1=Balić-Žunić|first1=Tonči|last2=Birkedal|first2=Renie|last3=Katerinopoulou|first3=Anna|last4=Comodi|first4=Paola|title=Dehydration of blödite, Na2Mg(SO4)2(H2O)4, and leonite, K2Mg(SO4)2(H2O)4|journal=European Journal of Mineralogy|date=20 September 2015|doi=10.1127/ejm/2015/0027-2487|url=http://eurjmin.geoscienceworld.org/content/early/2015/09/14/ejm.2015.0027-2487.abstract|volume=28|issue=1|pages=33–42|bibcode=2016EJMin..28...33B|url-access=subscription}} :2K2Mg(SO4)2·4H2O(s) → K2Mg2(SO4)3(s) + K2SO4(s) + 8H2O(g). ===Other physical properties=== The logarithmic [solubility product](/source/solubility_product) Ksp for leonite is −9.562 at 25 °C.{{cite journal|last1=Kwok|first1=Kui S.|last2=Ng|first2=Ka M.|last3=Taboada|first3=Maria E.|last4=Cisternas|first4=Luis A.|title=Thermodynamics of salt lake system: Representation, experiments, and visualization|journal=AIChE Journal|date=March 2008|volume=54|issue=3|pages=706–727|doi=10.1002/aic.11421|bibcode=2008AIChE..54..706K|url=http://www.uantof.cl/d2p/Ph.%20D.%20Luis%20Cisternas/Articles/Thermodynamics%20of%20salt%20lake%20system.pdf|archive-date=2016-03-05|access-date=2015-11-15|archive-url=https://web.archive.org/web/20160305183918/http://www.uantof.cl/d2p/Ph.%20D.%20Luis%20Cisternas/Articles/Thermodynamics%20of%20salt%20lake%20system.pdf|url-status=dead}} table 7 on page 716 The equilibrium constant log K at 25 °C is −3.979.{{cite journal|last1=Plummer|first1=L. N.|last2=Parkhurst|first2=D. L.|last3=Fleming|first3=G. W.|last4=Dunkle|first4=S. A.|title=A Computer Program Incorporating Pitzer's Equations for Calculation of Geochemical Reactions in Brines|journal=Water-Resources Investigation Report|date=1988|number=88–4153|page=8|doi=10.3133/wri884153 |bibcode=1988usgs.rept...62P |url=https://pubs.usgs.gov/wri/1988/4153/report.pdf|access-date=28 November 2015}} The chemical potential of leonite is μj°/RT = −1403.97.{{cite journal|last1=Harvie|first1=Charles E.|last2=Weare|first2=John H.|title=The prediction of mineral solubilities in natural waters: the Na-K-Mg-Ca-Cl-SO4-H2O system from zero to high concentration at 25 °C|journal=Geochimica et Cosmochimica Acta|date=July 1980|volume=44|issue=7|pages=981–997|doi=10.1016/0016-7037(80)90287-2|bibcode=1980GeCoA..44..981H}} Thermodynamic properties include [Δ''f''Go''k''](/source/Gibbs_free_energy) = −3480.79 kJ mol−1; [Δ''f''Ho''k''](/source/Helmholtz_free_energy) = −3942.55 kJ mol−1; and ΔCo''p,k'' = 191.32 J K−1 mol−1.{{cite journal|last1=Bhattacharia|first1=Sanjoy K.|last2=Tanveer|first2=Sheik|last3=Hossain|first3=Nazir|last4=Chen|first4=Chau-Chyun|title=Thermodynamic modeling of aqueous Na+–K+–Mg2+–SO42− quaternary system|journal=Fluid Phase Equilibria|date=October 2015|volume=404|pages=141–149|doi=10.1016/j.fluid.2015.07.002}} The infrared spectrum of sulfate stretching modes shows peaks in absorption at 1005, 1080, 1102, 1134 and 1209 cm−1. Sulfate bending mode causes a peak at 720, and lesser peaks at 750 and 840 cm−1. An OH stretching mode absorbs at 3238 cm−1. When temperatures reduce, the peaks move and/or narrow, and additional peaks may appear at phase transitions. When leonite is stored for exhibition, it must not be in a place with too much humidity, otherwise it hydrates more.{{cite book|last1=Thompson|first1=John M.A.|title=Manual of curatorship : a guide to museum practice|date=1992|publisher=Butterworth-Heinemann|location=Oxford|isbn=978-0750603515|page=431|edition=2nd|url=https://books.google.com/books?id=9gAwCgAAQBAJ&pg=PA431|access-date=24 November 2015}} ==Formation== Starting in 1897, [Jacobus Henricus van 't Hoff](/source/Jacobus_Henricus_van_'t_Hoff) investigated how different salts were formed as sea water evaporated in different conditions. His purpose was to discover how salt deposits are formed. His research formed the basis for the studies of the conditions in which leonite is formed.{{cite book|last1=Whetham|first1=William Cecil Dampier|title=A Treatise on the Theory of Solutions|series=Cambridge Natural Science Manuals|date=1902|publisher=The University Press|location=Cambridge|pages=403–406|url=https://books.google.com/books?id=8-g8AAAAIAAJ&pg=PA405|access-date=23 November 2015}} Leonite can form when a water solution of [potassium sulfate](/source/potassium_sulfate) and [magnesium sulfate](/source/magnesium_sulfate) is concentrated between the temperature range of {{convert|320|-|350|K|C}}. Above this temperature range, [langbeinite](/source/langbeinite) (K2Mg2(SO4)3) is formed. Below {{convert|320|K|C}}, [picromerite](/source/picromerite) (K2Mg(SO4)2·6H2O) crystallises.{{cite journal|last1=Wollmann|first1=Georgia|last2=Voigt|first2=Wolfgang|title=Solid–liquid phase equilibria in the system K2SO4–MgSO4–H2O at 318K|journal=Fluid Phase Equilibria|date=May 2010|volume=291|issue=2|pages=151–153|doi=10.1016/j.fluid.2009.12.005}} For solutions with more than 90% proportion MgSO4, [hexahydrite](/source/hexahydrite) (MgSO4·6H2O) crystallises preferentially, and below 60%, [arcanite](/source/arcanite) (K2SO4) forms. In mixtures of [potassium chloride](/source/potassium_chloride), [potassium sulfate](/source/potassium_sulfate), [magnesium chloride](/source/magnesium_chloride) and [magnesium sulfate](/source/magnesium_sulfate) at 35 °C in water, leonite can crystallise out in a certain composition range. The plot of the system forms boundaries of leonite with [potassium chloride](/source/potassium_chloride), potassium sulfate, and picromerite. As magnesium is enriched, a quadruple point with [kainite](/source/kainite) exists.{{cite journal|last1=Susarla|first1=V. R. K. S.|last2=Seshadri|first2=K.|title=Equilibria in the system containing chloride and sulphates of potassium and magnesium|journal=Proceedings of the Indian Academy of Sciences – Chemical Sciences|date=August 1982|volume=91|issue=4|pages=315–320|doi=10.1007/BF02842643|s2cid=92060161|url=https://link.springer.com/article/10.1007/BF02842643|url-access=subscription}} In salt (NaCl) saturated brine, leonite can be deposited from magnesium and potassium sulfate mixtures as low as 25 °C. The 25 °C isotherm of the system has leonite surrounded by [sylvine](/source/sylvine), picromerite, [astrakanite](/source/astrakanite), [epsomite](/source/epsomite), and kainite. [Sodium chloride](/source/Sodium_chloride) saturated [brine](/source/brine)s are formed by seawater evaporation, though seawater does not contain enough potassium to deposite leonite this way.{{cite journal|last1=M'nif|first1=A.|last2=Rokbani|first2=R.|title=Minerals successions crystallisation related to tunisian natural brines|journal=Crystal Research and Technology|date=January 2004|volume=39|issue=1|pages=40–49|doi=10.1002/crat.200310147|bibcode=2004CryRT..39...40M |s2cid=94365552 }} Leonite is precipitated in series solar ponds at the [Great Salt Lake](/source/Great_Salt_Lake).{{cite book|last1=Butts|first1=D.S.|editor1-last=Wallace Gwynn|editor1-first=J.|title=Great Salt Lake, a Scientific, Historical, and Economic Overview|date=June 1980|publisher=Utah Geological Survey|page=172|chapter-url=https://books.google.com/books?id=w55U-YtutS8C&pg=PA172|chapter=Chemistry of Great Salt Lake Brines in Solar Ponds|isbn=9781557910837}} When picromerite is heated to between 85 and 128 °C, it gives off steam to give leonite:{{cite journal|last1=Dhandapani|first1=M.|last2=Thyagu|first2=L.|last3=Prakash|first3=P. Arun|last4=Amirthaganesan|first4=G.|last5=Kandhaswamy|first5=M. A.|last6=Srinivasan|first6=V.|title=Synthesis and characterization of potassium magnesium sulphate hexahydrate crystals|journal=Crystal Research and Technology|date=April 2006|volume=41|issue=4|pages=328–331|doi=10.1002/crat.200510582|bibcode=2006CryRT..41..328D |s2cid=96857276 }}{{cite journal|last1=Song|first1=Yuehua|last2=Xia|first2=Shupin|last3=Wang|first3=Haidong|last4=Gao|first4=Shiyang|title=Thermal behavior of double salt schoenite|journal=Journal of Thermal Analysis|date=July 1995|volume=45|issue=1–2|pages=311–316|doi=10.1007/bf02548695|s2cid=95607489}} :K2Mg(SO4)2·6H2O(s) → K2Mg(SO4)2·4H2O(s) + 2H2O(g). ==Reactions== When leonite is dissolved in nitric acid and then crystallised, an acid potassium magnesium double sulfate is formed: KHMg(SO4)2·2H2O.{{cite journal|last1=Meyerhoffer|first1=Wilhelm|last2=Cottrell|first2=F. G.|title=An Acid Triple Salt|journal=Journal of the Chemical Society, Abstracts|date=1901|volume=80|page=552|doi=10.1039/CA9018005548}} Originally in Zeit. Anorg. Chem. 1901, 27, 442-444. Leonite heated with hydrated magnesium sulfate in an equimolar ratio at 350 °C produces langbeinite:{{cite patent| country = US| number = 3726965| status = | title = Production of langbeinite from a potassium magnesium sulfate salt and magnesium sulfate | pubdate = 10 April 1973 | invent1 = F. Andreasen | invent2 = U. Neitzel}} :K2Mg(SO4)2·4H2O(s) + MgSO4·''x''H2O(s) → K2Mg2(SO4)3(s) + (4 + ''x'')H2O(g). Potassium chloride solution can convert leonite to solid potassium sulfate: :2KCl(aq) + K2Mg(SO4)2·4H2O(s) → 2K2SO4(s) + MgCl2(aq). More potassium sulfate can be precipitated by adding [ethylene glycol](/source/ethylene_glycol).{{cite patent| country = US| number = 4195070|title=Preparation of a MgCl2 solution for Nalco's MgCl2 process from MgSO4 and other MgSO4 salts|pubdate=25 March 1980|invent1=Ronald J. Allain|invent2=David G. Braithwaite|invent3=Joseph P. Maniscalco}} [Fluorosilicic acid](/source/Fluorosilicic_acid) in water reacts with leonite to produce insoluble [potassium fluorosilicate](/source/potassium_fluorosilicate) and a solution of magnesium sulfate and sulfuric acid:{{cite patent| country = US| number = 3082061| status = | title = Production of potassium fluosilicate| pubdate = 19 March 1960 | invent1 = Raymond L. Barry | invent2 = Woodrow W. Richardson }} :H2SiF6(aq) + K2Mg(SO4)2·4H2O(s) → K2SiF6(s) + MgSO4(aq) + H2SO4(aq). Between 15 and 30 °C, a 22% magnesium chloride solution will react with leonite or picromerite to yield solid potassium chloride and hydrated magnesium sulfate.{{cite patent| country = US| number = 3533735| status = | title = Production of potassium chloride from schoenite and from brines containing potassium, magnesium, chloride and sulfate | pubdate = 13 October 1970 | invent1 = Jerome A. Lukes}} ==Natural occurrence== Leonite can form during the dehydration of seawater or lakewater. Leonite can be a minor primary constituent of [evaporite](/source/evaporite) [potash](/source/potash) deposits, or a secondary mineral.{{cite book|last1=Stewart|first1=Frederick H.|editor1-last=Fleischer|editor1-first=Michael|title=Data of Geochemistry|date=1963|publisher=United States Government Printing Office|location=Washington|page=Y10–Y25|edition=6|chapter-url=https://pubs.usgs.gov/pp/0440y/report.pdf|chapter=Y. Marine Evaporites}} In order to form leonite from seawater, the brine must separate from the deposited solids so that reactions do not happen with earlier deposited salts, and the temperature must be around 32 °C. Below 25° or above 40°, the content of the brine will not be suitable to deposit leonite. At this temperature, blodite deposits first, and then leonite, constituting only 3.2% of the [bittern](/source/bittern_(salt)) salts. Secondary reactions can produce or consume leonite in evaporite deposits. Leonite can convert to [polyhalite](/source/polyhalite), and [kieserite](/source/kieserite) can be changed to leonite, Groundwater penetrating bittern salt deposits can convert some to leonite, particularly in the cap regions of salt domes. Leonite was first found in nature in the Stassfurt Potash deposit, [Westeregeln](/source/Westeregeln), [Egeln](/source/Egeln), Saxony-Anhalt, Germany. The Stassfurt salt deposits are from the [Permian](/source/Permian) period. They are under the Magdeburg-Halberstadt region in central Germany. The leonite occurs in the salt clay and [carnallite](/source/carnallite) beds, which are up to 50 meters thick.{{cite book|last1=Iglesrud|first1=Iver|title=Physics of the Earth V Oceanography|date=June 1932|publisher=National Research Council of the National Academy of Sciences|location=Washington DC|pages=184–195|chapter=Formation of Oceanic Salt Deposits|chapter-url=https://books.google.com/books?id=masrAAAAYAAJ&pg=PA184}} Other locations in Germany are the [Neuhof-Ellers Potash Works](/source/Neuhof-Ellers_Potash_Works) in [Neuhof](/source/Neuhof%2C_Hesse), [Fulda](/source/Fulda), Hesse; the [Riedel Potash Works](/source/Riedel_Potash_Works) in [Riedel-Hänigsen](/source/Riedel-H%C3%A4nigsen), Celle, Lower Saxony; [Aschersleben](/source/Aschersleben); [Vienenburg](/source/Vienenburg); and [Leopoldshall](/source/Leopoldshall). Outside Germany, it is found at [Vesuvius](/source/Vesuvius), Italy; [Stebnyk](/source/Stebnyk), Ukraine; and the [Carlsbad potash district](/source/Carlsbad_potash_district), [Eddy County](/source/Eddy_County%2C_New_Mexico), New Mexico, US. It is found in crystalline [speleothem](/source/speleothem)s in [Tăuşoare Cave](/source/T%C4%83u%C5%9Foare_Cave) in Romania; here it occurs with [konyaite](/source/konyaite) (K2Mg(SO4)2·5H2O), [syngenite](/source/syngenite) (K2Ca(SO4)2·H2O), [thenardite](/source/thenardite) (Na2SO4), and [mirabilite](/source/mirabilite) (Na2SO4·10H2O).{{cite journal|last1=Onac|first1=B. P.|last2=White|first2=W. B.|last3=Viehmann|first3=I.|title=Leonite [K2Mg(SO4)2·4H2O], konyaite [Na2Mg(SO4)2·5H2O] and syngenite [K2Ca(SO4)2·H2O] from Tausoare Cave, Rodnei Mts, Romania|journal=Mineralogical Magazine|date=February 2001|volume=65|issue=1|pages=103–109|doi=10.1180/002646101550154|bibcode=2001MinM...65..103O|s2cid=128761889}} Leonite also occurs in Wooltana Cave, [Flinders Ranges](/source/Flinders_Ranges), South Australia.{{cite journal|last1=Snow|first1=Michael|last2=Pring|first2=Allan|last3=Allen|first3=Nicole|title=Minerals of the Wooltana Cave, Flinders Ranges, South Australia|journal=Transactions of the Royal Society of South Australia|date=November 2014|volume=138|issue=2|pages=214–230|doi=10.1080/03721426.2014.11649009|bibcode=2014TRSAu.138..214S |s2cid=85665430}} Soil in the [Gusev Crater](/source/Gusev_Crater) on Mars contains leonite as well as many other hydrated sulfates.{{cite journal|last1=Lane|first1=M. D.|last2=Bishop|first2=J. L.|last3=Darby Dyar|first3=M.|last4=King|first4=P. L.|last5=Parente|first5=M.|last6=Hyde|first6=B. C.|title=Mineralogy of the Paso Robles soils on Mars|journal=American Mineralogist|date=1 May 2008|volume=93|issue=5–6|pages=728–739|doi=10.2138/am.2008.2757|url=https://www.researchgate.net/publication/259313380|access-date=14 November 2015|bibcode=2008AmMin..93..728L|s2cid=56095205}} On [Europa](/source/Europa_(moon)), leonite is predicted to be stable, with a vapour pressure 10−13 that of ice. It is stable at pressures up to 10−7, above which a more hydrated salt exists. It should form up to 2% of the salts near the surface.{{cite journal|last1=Zolotov|first1=M. Yu.|last2=Shock|first2=E. L.|title=Thermodynamic Stability of Hydrated Salts on the Surface of Europa|journal=Lunar and Planetary Science|volume=XXXI|pages=1843|url=http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1843.pdf|bibcode=2000LPI....31.1843Z|year=2000}} Weathering of potassium-rich medieval glass forms a [weathering crust](/source/weathering_crust) that can contain leonite.{{cite journal|last1=Woisetschläger|first1=Gebhard|last2=Dutz|first2=Myriam|last3=Paul|first3=Sabine|last4=Schreiner|first4=Manfred|title=Weathering Phenomena on Naturally Weathered Potash-Lime-Silica-Glass with Medieval Composition Studied by Secondary Electron Microscopy and Energy Dispersive Microanalysis|journal=Microchimica Acta|date=27 November 2000|volume=135|issue=3–4|pages=121–130|doi=10.1007/s006040070001|s2cid=97530236}} ==Use== Leonite can be used directly as a [fertilizer](/source/fertilizer), contributing potassium and magnesium. It can be refined to K2SO4 for fertilizer use.{{cite book|last1=Foot|first1=D. G.|last2=Huiatt|first2=J. L.|last3=Froisland|first3=L. J.|title=Potash Recovery from Process and Waste Brines by Solar Evaporation and Flotation|date=1984|publisher=Bureah of Mines, United States Department of Interior|page=2|url=http://stacks.cdc.gov/view/cdc/10630/cdc_10630_DS1.pdf}} The process to convert leonite to potassium sulfate involves mixing it with a potassium chloride (a cheaper chemical) solution. The desired product, potassium sulfate, is less soluble and is filtered off. Magnesium chloride is very soluble in water. The filtrate is concentrated by evaporation, where more leonite crystallises, which is then recycled to the start of the process, adding more [langbeinite](/source/langbeinite) or picromerite.{{cite book|last1=Kirk|first1=Raymond Eller|last2=Othmer|first2=Donald Frederick|title=Kirk-Othmer Encyclopedia of Chemical Technology Volume 19 Pigments to Powders, Handling|date=1995|page=531|edition=4th|publisher=John Wiley}} Leonite may have been used in an alchemical formula to make "potable gold" around 300 AD in China. This was likely to be a liquid [colloid of gold](/source/Colloidal_gold).{{cite book|last1=Ping-Yü|first1=Ho|last2=Gwei-Djen|first2=Lu|last3=Needham|first3=Joseph|title=Science and civilisation in China.|date=1976|publisher=Cambridge University Press|location=Cambridge|isbn=978-0521210287|pages=75–98|edition=Reprinted|url=https://books.google.com/books?id=4sTb1KsvupgC&pg=PA89}} ==Related== Leonite is [isotypic](/source/isotypic) with the mineral [mereiterite](/source/mereiterite) (K2Fe(SO4)2·4H2O), and with artificial Mn-leonite (K2Mn(SO4)2·4H2O). Others with the same crystal structure include: : K2Cd(SO4)2·4H2O : (NH4)2Mg(SO4)2·4H2O : (NH4)2Mn(SO4)2·4H2O : (NH4)2Fe(SO4)2·4H2O : (NH4)2Co(SO4)2·4H2O and : K2Mg(SeO4)2·4H2O.{{cite journal|last1=Giester|first1=Gerald|last2=Rieck|first2=Branko|title=Mereiterite, K2Fe[SO4]2·4H2O, a new leonite-type mineral from the Lavrion Mining District, Greece|journal=European Journal of Mineralogy|date=19 May 1995|volume=7|issue=3|pages=559–566|doi=10.1127/ejm/7/3/0559|bibcode=1995EJMin...7..559G}} Myron Stein suggested using the name "leonite" for element 96, naming it after the constellation [Leo](/source/Leo_(constellation)). This name was not accepted and [curium](/source/curium) was the name assigned.{{cite journal|last1=Seaborg|first1=Glenn T.|title=Terminology of the transuranium elements|journal=Terminology|date=1994|volume=1|issue=2|pages=229–252|doi=10.1075/term.1.2.02sea}} ==References== {{Reflist|30em}} ==External links== {{Commons category|Leonite}} * {{cite web|url=http://www.phasediagram.dk/ternary/ternary3.htm|title=Aqueous Salt Solutions The MgSO4-K2SO4-H2O system}} * {{cite journal|last1=Starrs|first1=B. A.|last2=Storch|first2=H. H.|title=The Ternary System: Potassium Sulphate-Magnesium Sulphate-Water|journal=The Journal of Physical Chemistry|date=January 1929|volume=34|issue=10|pages=2367–2374|doi=10.1021/j150316a019}} public domain but paywalled * {{cite journal|last1=Madsen|first1=Beth M.|title=Loweite, Vanthoffite, Bloedite, and Leonite from Southeastern New Mexico|journal=Geological Survey Professional Paper|date=1966|volume=550|issue=2|pages=B125–B129|url=https://books.google.com/books?id=4holAQAAIAAJ&pg=SL2-PA125|access-date=14 November 2015}} * {{cite book|last1=Eberhard|first1=Usdowski|last2=Bach|first2=Martin F.|title=Atlas and Data of Solid-Solution Equilibria of Marine Evaporites|date=1998|publisher=Springer Science & Business Media|page=263|url=https://books.google.com/books?id=gxX_CAAAQBAJ&pg=PA263|isbn=9783642643354|doi=10.1007/9783642602849|doi-broken-date=12 July 2025}} includes 3D diagram of temperature vs Mg/K and Cl/SO4 with leonite showing up as a lozenge shaped cylinder {{Authority control}} Category:Sulfate minerals Category:Potassium minerals Category:Magnesium minerals Category:Tetrahydrate minerals Category:Monoclinic minerals Category:Minerals in space group 12 --- Adapted from the Wikipedia article [Leonite](https://en.wikipedia.org/wiki/Leonite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Leonite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.