{{Short description|Hydrocarbon mineral}} {{infobox mineral | name = Evenkite | boxwidth = | boxbgcolor = | image = Evenkite-444375.jpg | alt = | caption = Evenkite from Dubnik, Slovakia | category = Organic mineral | formula = C<sub>24</sub>H<sub>50</sub> | IMAsymbol = Evk<ref>{{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}}</ref> | molweight = | strunz = 10.BA.50 | dana = | system = Orthorhombic | class = Dipyramidal (mmm) <br/>H-M symbol: (2/m 2/m 2/m) | symmetry = ''Pbcm'' | unit cell = a = 7.47, b = 4.98, c = 65.85 [Å]; Z = 4 | color = Colorless or pale yellow | colour = | habit = Tabular pseudohexagonal crystals, granular, disseminated | twinning = Polysynthetic | cleavage = {001} Perfect | fracture = | tenacity = | mohs = 1 | luster = Waxy | streak = | diaphaneity = Transparent | gravity = 0.87 | density = | polish = | opticalprop = Biaxial (+) | refractive = n<sub>α</sub> = 1.504 n<sub>β</sub> = 1.504 n<sub>γ</sub> = 1.553 | birefringence = δ = 0.049 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref name=Mindat>[http://www.mindat.org/min-1428.html Mindat.org]</ref><ref name=Webmin>[http://webmineral.com/data/Evenkite.shtml Webmineral data]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/evenkite.pdf Handbook of Mineralogy]</ref><ref name=span1998/><ref name=jech2007/><ref name=skrop1953/><ref name=plant2006/><ref name=kote2006/><ref name=pilo2005/> }} '''Evenkite''' is a rare hydrocarbon mineral with formula C<sub>24</sub>H<sub>50</sub>; specifically, H<sub>3</sub>C–(CH<sub>2</sub>)<sub>22</sub>–CH<sub>3</sub>, the alkane ''n''-tetracosane.<ref name="kote2006" /> It occurs as very soft (Mohs hardness 1) transparent crystals, colorless to yellow, with a waxy luster. The softness is a characteristic of crystalline long-chain alkanes, which are the main constituents of paraffin wax.<ref name=pilo2005/>
Evenkite one of very few minerals that consist of crystalline hydrocarbons,<ref name=plant2006/><ref name=jech2007/> which include carpathite (pure crystalline coronene, a polyaromatic hydrocarbon).<ref name=echi2007/> It is also one of the few non-porous minerals that floats on water. It has been claimed to be the same as hatchettite.<ref name=span2000/>
==History and geologic occurrence== Evenkite was first described in 1953 by A. V. Shropyshev, as found in the Khavokiperskiye deposit, Lower Tunguska River, Evenkiysky District, Siberia, Russia, where it occurs inside geodes and vugs in a quartz vein in welded tuff.<ref name=skrop1953/> It was named after the district.<ref name=Webmin/> It has also been reported from the Hautes-Alpes region in France and the Slanské and Vihorlat mountains of Slovakia.<ref name=Mindat/>
Evenkite appears as flaky wax partials on top of the quartz crystals.<ref name=span1998/> Associated minerals include quartz, chalcedony, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and calcite.<ref name=HBM/>
Evenkite was the last part of the geode to form.<ref name=span1998/> It is believed to have resulted from thermal cracking of the organic matter (mainly marine plants) that where trapped in the septarian concretions during the Jurassic burial, as the buried sediments were subjected to high pressure and temperatures.<ref name=jech2007/> The French Alps region received a lot of geological uplift after the Jurassic burial.<ref name=span1998/>
==See also==
==References== <references> <ref name=skrop1953>Skropyshev, A.V. "On Paraffin from a Base Metal Vein". Doklady Acad, 1953, P.717-719.</ref>
<ref name=span1998>Spangenberg, J.E. and Meisser, N. "Geochemistry of the organic mineral evenkite in septarian concretions in the Oxfordian marls of the French Alps". Mineralogical Magazine, 1998, p.1436-1437.</ref>
<ref name=span2000>J. E. Spangenberg and N. Meisser (2000): ""Hatchettite and Evenkite - two mineral names for the same natural crystalline paraffinic vax[isotope ratio study]". Paper EDB-00:118740 ''Abstracts of the 5th Isotope Workshop of European Society for Isotope Research'', pages 188-191. {{isbn|83-912388-8-1}}</ref>
<ref name=pilo2005>Pilonen, P.C. and Ercit, T.S. "New Mineral Names". American Mineralogist, 2005, p.1466-1469.</ref>
<ref name=plant2006>Platonova, N.V. and Kotel'nikova, E.N. "Synthesis of Organic Mineral Evenkite". Geology of Ore Deposits, 2006, p.87-91.</ref>
<ref name=kote2006>Kotel'nikova, E.N., Platonova, N.V., and Filatov, G.M. "Identification of Biogenic Paraffins and Their Thermal Phase Transitions". Geology of Ore Deposits, 2006, p.607-709.</ref>
<ref name=jech2007>Jechlicka, J., Villar, S., and Edwards, G.M. "Raman spectroscopy of natural accumulated paraffins from rocks: Evenkite, ozokerite, and hatchtine". Spectrochimica Act, 2007, p.1143-1148.</ref>
<ref name=echi2007>Takuya Echigo, Mitsuyoshi Kimata, and Teruyuki Maruoka (2007): "Crystal-chemical and carbon-isotopic characteristics of karpatite (C<sub>24</sub>H<sub>12</sub>) from the Picacho Peak Area, San Benito County, California: Evidences for the hydrothermal formation". ''American Mineralogist'', volume 92, issues 8-9, pages 1262–1269. Note: the name should be spelled "carpathite". {{doi|10.2138/am.2007.2509}}</ref>
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{{Commons category|Evenkite|position=left}}
Category:Organic minerals Category:Orthorhombic minerals Category:Minerals in space group 57 Category:Luminescent minerals Category:Minerals described in 1953