Huntiteis acarbonate mineralwith the chemical formula Mg3Ca(CO3)4.[4]Huntite crystallizes in thetrigonalsystem and typically occurs as platy crystals and powdery masses. For most of recorded history its main use was as a white pigment.[5][6]Today the most common industrial use of huntite is as a natural mixture withhydromagnesiteas aflame retardantorfire retardantadditive for polymers.
Huntite | |
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General | |
Category | Carbonate mineral |
Formula (repeating unit) | Mg3Ca(CO3)4 |
IMA symbol | Hun[1] |
Strunz classification | 5.AB.25 |
Dana classification | 14.04.03.01 |
Crystal system | Trigonal |
Crystal class | Trapezohedral (32) H-M symbol:(3 2) |
Space group | R32 |
Unit cell | a = 9.505 Å, c = 7.821 Å; Z = 3 |
Identification | |
Formula mass | 353 g/mol |
Color | White, lemon white |
Crystal habit | Platy crystals; compact chalklike masses |
Fracture | Subconchoidal |
Tenacity | Brittle |
Mohs scalehardness | 1–2 |
Luster | Earthy (dull) |
Streak | White |
Diaphaneity | Translucent |
Specific gravity | 2.696 |
Optical properties | Uniaxial (–) |
Refractive index | nω= 1.622 nε= 1.615 |
References | [2][3][4] |
Discovery
editIn 1953 a paper by George Faust[7]announced the discovery of a new carbonate mineral found in Currant Creek, Nevada (US). Faust acknowledged that the mineral probably had been discovered previously, but it had been misidentified as impure magnesite by W. E. Ford in 1917. Faust named the new mineral "huntite" in honour of his former teacher, Walter Frederick Hunt (1882–1975),[8]Professor of Petrology at the University of Michigan.[9]Faust carried out analyses of the mineral, and found amongst others that in differential thermal analysis huntite showed two endothermic peaks, which could be attributed to the dissociation of MgCO3and CaCO3respectively. Chemical analyses showed huntite to consist of Mg3Ca(CO3)4.
Properties
editHuntite often occurs in combination with other Mg/Ca carbonates such asdolomite,magnesite,andhydromagnesite.Large deposits of huntite occur inTurkeyandGreeceand these are commercially exploited because of its fire retardant properties. Huntite thermally decomposes over a temperature range of about 450–800 °C, releasingcarbon dioxideand leaving a residue ofmagnesiumandcalcium oxides.[10][11][12]
Occurrences
editHuntite has been found in a variety of environments. For example, it occurs in the modern carbonate sediments of the tidal flats bordering thePersian Gulf,[13]in seasonal salt lakes of Turkey,[14][15][16][17]in various playa lakes ofBritish Columbia(Canada),[18]in lacustrine deposits of Greece[19]and in modern sabkha sediments in Tunisia.[20][21]
Caves seem to be well suited for the low-temperature formation of huntite. For example, it has been reported from the caves of theCarlsbad Caverns National Park,New Mexico (US);[22][23][24]in theCastleguard Cave(Alberta, Canada);[25]in the Grotte de Clamouse,France;[26][27]in various caves of theTransvaal ProvinceofSouth Africa;[28]inClearwater Cave,Mulu, Sarawak[29]in theJenolan Caves,Australia;[30]and in the Castañar Cave near Cáceres,Spain.[31][32]
Syntheses
editIn 1962, huntite was first synthesized by Biedl and Preisinger in experiments conducted at 100 °C and 3.2 bar CO2pressure.[33]
In 1983 Oomori et al. claimed laboratory synthesis of huntite at 33 °C when adding asodium carbonatesolution to concentrated sea water saturated withcalcium bicarbonate.[34] In 2006, Zaitseva et al. noted the precipitation of huntite at room temperature and atmospheric pressure. In laboratory experiments originally intended to synthesize magnesium calcite, they had added cultures ofMicrocoleus chtonoplastes(cyanobacteria) to sea water brine. After 10 months of continuously shaking the samples they found huntite,magnesite,andaragonite.[35] In 2012, Hopkinson et al. synthesized the mineral at 52 °C by reacting magnesium calcite withnesquehonite(MgCO3·3H2O).[36]
Genesis
editHuntite,dolomiteand magnesite appear to be so very closely related, that a genetic relationship seems to be implied.[37]In a number of instances all three carbonates are found in close association; for example Faust (1953) described huntite occurring together with dolomite and magnesite (amongst other minerals); Carpenter (1961)[38]found huntite associated with aragonite, magnesium calcite and dolomite; Larrabee (1969)[39]reported on huntite together with (amongst many others) aragonite,calcite,dolomite and magnesite inserpentiniteon a weatheredduniterock. A weatheredbasaltin Australia was found to contain huntite in association with magnesite (Cole & Lancucki, 1975[40]). Huntite together with magnesite was found by Calvo et al. (1995)[41]in lake sediments of Northern Greece. Huntite in combination with magnesite occurs in a weathered serpentinite near Hrubšice,Czech Republicaccording to Němec (1981)[42]According to the mineral and locations database of "mindat.org" huntite, together with aragonite, calcite, dolomite and magnesite can be found in the "U Pustého Mlýna" quarry near Hrubšice, Czech Republic.[3]
Industrial use
editThe most common industrial use of huntite is as a natural mixture withhydromagnesiteas aflame retardantorfire retardantadditive for polymers.[43][44][45]The heat of a fire will cause huntite to decompose releasing carbon dioxide into the flames. This helps to slow the spread of the fire. The release of carbon dioxide isendothermic,meaning that it takes in heat, this action helps to cool the burning material, again slowing the spread of the fire. These types of mixtures are used as alternatives to the more commonly usedaluminium hydroxide.
Conite
editA mineral with exactly the same composition as that of huntite has been known for more than 200 years; in 1812 for example, John[46]and Stromeyer[47]described it as having a chemical composition of CaCO3:MgCO3= 1: 3. In those days the mineral was known asconite(in German: Konit); a name given to it by Retzius (1798).[48]However, a serious problem concerns the exact location where the mineralconitecan be found. Originally Retzius had found the new carbonate in a mineral collection, and had recognized it as a new species because it was harder than any of the known carbonates (even so hard, that it would spark when struck with steel) but no indication was given as to the site where thisconitehad been found.[48]A number of papers describingconiteare known, without the exact location where it can be found. In 1804, Ludwig stated that the sample ofconitestudied by him, came "from Iceland".[49]In 1805 Leonhard wrote that theconitehe had analyzed, came "from Scandinavia".[50]Somewhat more exact was Stromeyer in 1812, who claimed that his sample ofconitehad been found near the village of Frankenhayn, on the eastern slope of theHoher MeissnernearKassel,Germany. However, thisconitehad been found there as a loose boulder, and no outcrop of the new mineral was mentioned. In 1833 Blum summed up howconitecould be found in mines nearFreiberg(Germany), as boulders on the slopes of Mount Meissner (Germany) and on Iceland.[51]In 1849, Hirzel repeated thatconitecould be found on the eastern slope of Mount Meissner,[52]and in 1882 Schrauf reported the mineral from the magnesite deposits on the borders of the Schöninger Bach atKřemženear Budweis, Czech Republic.[53] Because of the absence of a type locality for the mineralconite,a historical priority of its description over that of huntite cannot be claimed.
References
edit- ^Warr, L.N. (2021)."IMA–CNMNC approved mineral symbols".Mineralogical Magazine.85(3): 291–320.Bibcode:2021MinM...85..291W.doi:10.1180/mgm.2021.43.S2CID235729616.
- ^Handbook of Mineralogy: Huntite
- ^abHuntite on Mindat.org
- ^abHuntite on Webmineral
- ^John Clarke, "Two Aboriginal Rock Art Pigments from Western Australia: Their Properties, Use, and Durability." Studies in Conservation, Volume 21, Issue 3 (1976) pp. 134–142https://doi.org/10.1179/sic.1976.023
- ^Richard Parkinson, The Painted Tomb-Chapel of Nebamun: Masterpiece of Ancient Egyptian Art in the British Museum (The British Museum Press: London, 2008) page 50
- ^Faust, GT (1953)."Huntite A New Mineral".American Mineralogist.38:4–24.[1]
- ^Kraus, E.H., American Mineralogist, v. 38, Jan–Feb, 1953
- ^Ramsdell, LS (1958)."Presentation of the Roebling Medal to Walter F Hunt".American Mineralogist.43:334–335.
- ^Ozao, R; Otsuka, R. (1985). "Thermoanalytical Investigation of Huntite".Thermochimica Acta.86:45–58.doi:10.1016/0040-6031(85)87032-5.
- ^Hollingbery, LA; Hull TR (2010)."The Thermal Decomposition of Huntite and Hydromagnesite - A Review".Thermochimica Acta.509(1–2): 1–11.doi:10.1016/j.tca.2010.06.012.
- ^Hollingbery, LA; Hull TR (2012)."The Thermal Decomposition of Natural Mixtures of Huntite and Hydromagnesite".Thermochimica Acta.528:45–52.doi:10.1016/j.tca.2011.11.002.
- ^Kinsman, D. J. J. (1967): Huntite from a carbonate – evaporite environment. American Mineralogist, vol. 52, pp. 1332–1340.[2]
- ^Irion, G. & Müller, G. (1968): Huntite, dolomite, magnesite and polyhalite of Recent age from Tuz Gölü, Turkey. Nature, vol. 220, pp. 1309–1310.
- ^Irion, G. (1970): Mineralogisch-sedimentpetrographische und geochemische Untersuchungen am Tuz Gölü (Salzsee). Chemie der Erde, vol.29, pp. 163–226.
- ^Camur, M. Z. & Mutlu, H. (1996): Major-ion geochemistry and mineralogy of the Salt-Lake (Tuz Gölü) basin, Turkey. Chemical Geology, vol.127, pp. 313–329.
- ^Mutlu, H.; Kadir, S. & Akbulut, A. (1999): Mineralogy and water chemistry of the Lake Acigöl, Denizli, Turkey. Carbonates and Evaporites, vol. 14, pp. 191–199.
- ^Renaut, R. W. (1990): Recent carbonate sedimentation and brine evolution in the saline lake basins of the Cariboo Plateau, British Columbia, Canada. pp. 67–81, in: Comin, F. A. & Northcote, T. G. (eds.): Saline Lakes. Kluwer, Dordrecht.
- ^Wetzenstein, W. (1974): Sedimentpetrographische Untersuchungen an limnischen Magnesit – Huntitlagerstätten im Plio-Pleistozän des Serviabeckens / Nordgriechenland. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 1974, pp. 625–642.
- ^Perthuisot, J. P. (1971): Présence de magnésite et de huntite dans le sebkha el Melah de Zarzis. Comptes Rendus des Séances de l'Académie des Sciences de Paris, Série D, vol. 272, pp. 185–188.[3]
- ^Perthuisot, J. P. (1974): Les dépôts salins de la sebkha El Melah de Zarzis: Conditions et modalités de la sédimentation évaporitique. Revue de la geographie physique et de géologie dynamique, vol. 16, pp. 177–187.
- ^Thrailkill, J. (1971): Carbonate deposition in Carlsbad caverns. Journal of Geology, vol. 79, pp. 683–695.
- ^Hill, C. A. (1973): Huntite flowstone in Carlsbad Caverns, New Mexico. Science, vol. 181, pp. 158–159.
- ^Gonzalez, L. A. & Lohmann, K. C. (1988): Controls on mineralogy and composition of spelean carbonates: Carlsbad Caverns, New Mexico. pp. 81–101, in: James, N. P. & Choquette, P. W. (eds.): Paleokarst. Springer, New York, 416 p.
- ^Harmon, R. S.; Atkinson, T. C. & Atkinson, J. L. (1983): The Mineralogy of Castleguard Cave, Columbia Icefields, Alberta, Canada].Arctic and Alpine Research,vol. 15, pp. 503–522.
- ^Baron, G.; Caillère, S.; Lagrange, R. & Pobeguin, T. (1957): Sur la présence de huntite dans une grotte de l'Hérault (la Clamouse). Comptes Rendus hebdomadaires des séances de l'Académie des Sciences (Paris), vol. 245, pp. 92–94.[4]
- ^Fischbeck, R. (1976): Mineralogie und Geochemie carbonatischer Ablagerungen in europäischen Höhlen – ein Beitrag zur Bildung und Diagenese von Speleothemen. Neues Jahrbuch für Mineralogie, Abhandlungen, vol. 126, pp. 269–291.
- ^Martini, J. & Kavalieris, I. (1978): Mineralogy of the Transvaal caves. Transactions of the Geological Society of South Africa, vol. 81, pp. 47–54.
- ^Laverty, M. (1982): Cave Minerals in the Gunung Mulu National Park, Sarawak. Cave Science 9(2), p. 130
- ^Pogson, R. E.; Osborne, R. E. & Colchester, D. M. (2001): Minerals of the Jenolan Caves – geosphere meets biosphere. Journal and Proceedings of the Royal Society of New South Wales, vol. 134, p. 111.[5]
- ^Alonso-Zarza, A. M.; Martín-Pérez, A.; Gil-Peña, I.; Martínez-Flores, E. & Muñoz-Barco, P. (2005): Formacíon de dolomita y huntita en depósitos de moon-milk en la Cueva de Castañar de Ibo (Cáceras). Geogaceta, July 2005, no. 38, pp. 247–250.[6]
- ^Alonso-Zarza, A. M. & Martín-Pérez, A. (2008): Dolomite in caves: Recent dolomite formation in oxic, non-sulfate environments, Castañar Cave, Spain. Sedimentary Geology, vol. 205, pp. 160–164.
- ^Biedl, A. & Preisinger, A. (1962): Synthese von Huntit, Mg3Ca(CO3)4.Anzeiger der mathematisch-naturwissenschaftliche Klasse, Österreichische Akademie der Wissenschaften (Wien), 1962, No.10, pp.148–149.
- ^Oomori, T.; Kaneshima, K.; Taira, T. & Kitano, Y. (1983): Synthetic studies of protodolomite from brine waters. Geochemical Journal, vol.17, pp.147–152.
- ^Zaitseva, L. V.; Orleanskii, V. K.; Gerasimenko, M. & Ushatinskaya, G. T. (2006): The role of cyanobacteria in crystallization of magnesium calcites. Paleontological Journal, vol.40, pp.125–133.
- ^Hopkinson, L.; Kristova, P.; Rutt, K. & Cressey, G. (2012): Phase transitions in the system MgO – CO2– H2O during CO2degassing of Mg-bearing solutions. Geochimica et Cosmochimica Acta, vol.76, pp.1–13.
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- ^Larrabee, D. M. (1969) Serpentinite and rodingite in the Hunting Hill Quarry, Montgomery County, Maryland. U.S. Geological Survey Bulletin, no.1283, 34 p.[7]
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- ^Calvo, J. P.; Stamatakis, M. G. & Magganas, A. C. (1955): Clastic huntite in Upper Neogene formations of theKozani Basin,Macedonia,Northern Greece. Journal of Sedimentary Research, vol.A65, pp.627–632.
- ^Němec, D. (1981): Huntit ze serpentinitové oblasti u Hrubšic na západni Moravě (Huntite from the serpentinite area at Hrubšice, Western Moravia – English summary). Časopis pro mineralogii a geologii, vol.26, pp.75–78.
- ^Hollingbery, LA; Hull TR (2010)."The Fire Retardant Behaviour of Huntite and Hydromagnesite – A Review".Polymer Degradation and Stability.95(12): 2213–2225.doi:10.1016/j.polymdegradstab.2010.08.019.
- ^Hollingbery, LA; Hull TR (2012)."The Fire Retardant Effects of Huntite in Natural Mixtures with Hydromagnesite".Polymer Degradation and Stability.97(4): 504–512.doi:10.1016/j.polymdegradstab.2012.01.024.
- ^Hull, TR; Witkowski A; Hollingbery LA (2011)."Fire Retardant Action of Mineral Fillers".Polymer Degradation and Stability.96(8): 1462–1469.doi:10.1016/j.polymdegradstab.2011.05.006.S2CID96208830.
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- ^Stromeyer, F. (1812): Analyse des sogenannten Konits vom Meissner. Annalen der Physik, vol.41, pp.336–338.[10]
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