Evenkite is a rare

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

mineral with formula C₂₄H₅₀; specifically, H₃C–(CH₂)₂₂–CH₃, the

alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whi ...

''n''-

tetracosane Tetracosane, also called ''tetrakosane'', is an alkane hydrocarbon with the structural formula H(CH2)24H. As with other alkanes, its name is derived from Greek for the number of carbon atoms, 24, in the molecule. It has 14,490,245 constitutional is ...

. It occurs as very soft (

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

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 Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...

. Evenkite one of very few minerals that consist of crystalline hydrocarbons, which include carpathite (pure crystalline coronene, a polyaromatic hydrocarbon). It is also one of the few non-porous minerals that floats on water. It has been claimed to be the same as hatchettite.

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 Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

, where it occurs inside

geode A geode (; ) is a geology, geological secondary formation within sedimentary rock, sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crys ...

s and

vug A vug, vugh, or vugg () is a small- to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity ( folding and faulting) are partially filled by quartz, calc ...

s in a

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

in welded tuff. It was named after the district. It has also been reported from the

Hautes-Alpes Hautes-Alpes (; ; ) is a Departments of France, department in the Provence-Alpes-Côte d'Azur Regions of France, region of Southeastern France. It is located in the heart of the French Alps, after which it is named. Hautes-Alpes had a population ...

region in France and the Slanské and Vihorlat mountains of

Slovakia Slovakia, officially the Slovak Republic, is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the west, and the Czech Republic to the northwest. Slovakia's m ...

. Evenkite appears as flaky wax partials on top of the quartz crystals. Associated minerals include quartz,

chalcedony Chalcedony ( or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic ...

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

pyrrhotite Pyrrhotite (''Pyrrhus of Epirus, pyrrhos'' in Greek language, Greek meaning "flame-coloured"'')'' is an iron sulfide mineral with the formula Fe(1−x)S (x = 0 to 0.125). It is a nonstoichiometric compound, nonstoichiometric variant of FeS, th ...

sphalerite Sphalerite is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in Sedimentary exhalative deposits, sedimentary exhalative, Carbonate-hoste ...

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crysta ...

chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a Mohs scale, hardness of 3.5 to 4 ...

and

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Evenkite was the last part of the geode to form. It is believed to have resulted from thermal cracking of the organic matter (manly marine plants) that where trapped in the septarian concretions during the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

burial, as the buried sediments were subjected to high pressure and temperatures. The

French Alps The French Alps are the portions of the Alps mountain range that stand within France, located in the Auvergne-Rhône-Alpes and Provence-Alpes-Côte d'Azur regions. While some of the ranges of the French Alps are entirely in France, others, such a ...

region received a lot of geological uplift after the Jurassic burial.

References

Skropyshev, A.V. "On Paraffin from a Base Metal Vein". Doklady Acad, 1953, P.717-719. 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. J. E. Spangenberg and N. Meisser (2000): ""Hatchettite and Evenkite - two mineral names for the same natural crystalline paraffinic vax sotope ratio study. Paper EDB-00:118740 ''Abstracts of the 5th Isotope Workshop of European Society for Isotope Research'', pages 188-191. Pilonen, P.C. and Ercit, T.S. "New Mineral Names". American Mineralogist, 2005, p.1466-1469. Platonova, N.V. and Kotel'nikova, E.N. "Synthesis of Organic Mineral Evenkite". Geology of Ore Deposits, 2006, p.87-91. 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. 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. Takuya Echigo, Mitsuyoshi Kimata, and Teruyuki Maruoka (2007): "Crystal-chemical and carbon-isotopic characteristics of karpatite (C₂₄H₁₂) 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". {{Commons category, Evenkite, position=left Organic minerals Orthorhombic minerals Minerals in space group 57 Luminescent minerals Minerals described in 1953

History and geologic occurrence

See also

References