Krutovite is a cubic

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

diarsenide with a chemical composition of NiAs₂ and a

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

content of 0.02-0.34 weight percent. Krutovite is composed of nickel and

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...

with trace to minor amounts of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

, sulfur, and

antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient time ...

.Vinogradova, R. A.; Rudashevskiy, N. S.; Bud'ko, I. A.; Bochek, L. I.; Kaspar, P.; Padera, K. (1977) Krutovite, a new cubic nickel diarsenide. International Geology Review, Vol. 19, Issue 2, pp. 232–244

Geological occurrence

Krutovite occurs in the Geshiber vein, Svornost shaft, 8th level, in the northwest strike of

Jáchymov Jáchymov (); german: Sankt Joachimsthal or ''Joachimsthal'') is a spa town in Karlovy Vary District in the Karlovy Vary Region of the Czech Republic. It has about 2,300 inhabitants. The historical core of the town from the 16th century is we ...

.Veselovský F.; Ondruš P; Gabašová A.; Hloušek J.; Vlašimský P.; Chernyshev IV (2003) Who was who in Jáchymov mineralogy II.: Journal of the Czech Geological Society, Vol 48, Issue 3-4, pp. 193 – 205 Jáchymov is a

Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus' Places * Czech, ...

mineral town in the St. Joachim's valley of the Ore Mountains. The Ore Mountains, also known as Krušné hory, are composed of two parts: the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

s and the Lower

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

metamorphic

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

sequence.Ondruš, P.; Veselovský, F.; Gabašová, A.; Hloušek, J.; Šrein, V. (2003) Geology and hydrothermal vein system of the Jáchymov (Joachimsthal) ore district.

Journal of the Czech Geological Society ''Journal of Geosciences'' (1956-1992 ''Časopis pro mineralogii a geologii'', 1993-2006: ''Journal of the Czech Geological Society'') is a peer-reviewed scientific journal published by the Czech Geological Society and its predecessors since 1956. ...

, Vol.48, Issue 3-4, pp 3–18 The surrounding area lies on fault zones where many minerals develop. The Potucky ore district where krutovite was originally found lies on the northern fault zone. Heading south is the Krušné hory

fault zone In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

which surrounds the district of the Jáchymov. The western border is the Central Fault and the eastern border is formed by the Plavno Fault.

Veins Veins are blood vessels in 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 the pulmonary and umbilical veins, both of which carry oxygenated b ...

come from the major fault lines where krutovite crystallized at moderate

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

temperatures. The veins can be classified into two categories: the morning veins striking along the east and west fault zone and the midnight veins striking from north to south. Krutovite comes from the midnight vein in the Svornmost mine which contains nickel ores as deep as 100 meters in the

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

body. The midnight veins are known to exhibit frequent variations in their

strike and dip Strike and dip is a measurement convention used to describe the orientation, or attitude, of a planar geologic feature. A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination m ...

and have an average width of 10–30 cm. In addition to nickel being mined here, silver, bismuth, and uranium were also found in the 19th century. Krutovite forms grains up to 0.1 mm in isometric or irregular form and has also been known to occur intergrowth with nickel

skutterudite Named after Skuterudåsen, a hill in Modum, Norway, skutterudite is a cobalt arsenide mineral containing variable amounts of nickel and iron substituting for cobalt with the ideal formula CoAs3. Some references give the arsenic a variable formula ...

and sometimes with

tennantite Tennantite is a copper arsenic sulfosalt mineral with an ideal formula . Due to variable substitution of the copper by iron and zinc the formula is . It is gray-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedri ...

. When this occurs the intergrowth is smooth and there is no visible reaction.Spiridonov, E. M.; Chvileva, T. N. (1996) The boundary between gersdorffite NiAsS and krutovite NiAs. Transactions Doklady of the Russian Academy of Sciences. Earth Science Sections, Vol. 344, Issue 7, pp. 119–123

Structure

Krutovite is from the family of the isometric-dipoloidal system (2/m) and is known to have the same structure type as

gersdorffite Gersdorffite is a nickel arsenic sulfide mineral with formula NiAsS. It crystallizes in the isometric system showing diploidal symmetry. It occurs as euhedral to massive opaque, metallic grey-black to silver white forms. Gersdorffite belongs to ...

type P2₁3. Krutovite and gersdorffite form a

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word ...

at a temperature of less than .

Physical properties

Krutovite is opaque grayish white paler then the color of nickel

. In reflected light the mineral has a vivid white with a rosy tint. It has a hardness of 5.5 on the Mohs scale and a metallic luster. No cleavage is observed. Krutovite has high degree of reflectance about 64.0-67.0% higher than known nickel arsenides and sulfarsenides. The spectrum of reflectance that occurs in krutovite has a wavelength range of 440-1100 and a minimum of 480-540 nm. The rose tint gives the small increase of reflectance in the violent and red parts of the spectrum.

Biographic sketch

Kruotvite was named in honor of

Georgi Alekseyevich Krutov Georgi may refer to: * Georgi (given name) * Georgi (surname) See also *Georgy (disambiguation) *Georgii (disambiguation) Georgii may refer to: ;Given name * Georgii Zantaraia (born 1987), Ukrainian judoka of Georgian origin * Georgii Karpechenko ...

(24 April 1902 - 11 December 1989) who was a

professor Professor (commonly abbreviated as Prof.) is an Academy, academic rank at university, universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a "person who pr ...

of mineralogy of

Moscow University M. V. Lomonosov Moscow State University (MSU; russian: Московский государственный университет имени М. В. Ломоносова) is a public research university in Moscow, Russia and the most prestigious ...

in Russia. Krutov graduated at the Geology Prospecting Faculty of the Moscow Mining Academy in 1931. He studied the Co-Ni deposits in the

Urals The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through European ...

and

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...

; cobalt in Dashkesan deposit, nickel in silicate ores in

ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...

massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

s of the Southern Ural, the Cu-Ni (Co) deposits of

Norilsk Norilsk ( rus, Нори́льск, p=nɐˈrʲilʲsk, ''Norílʹsk'') is a closed city in Krasnoyarsk Krai, Russia, located south of the western Taymyr Peninsula, around 90 km east of the Yenisey River and 1,500 km north of Krasnoyarsk. Norilsk i ...

in the Kranoyarsk region and Monchegorsk in

Karelia Karelia ( Karelian and fi, Karjala, ; rus, Каре́лия, links=y, r=Karélija, p=kɐˈrʲelʲɪjə, historically ''Korjela''; sv, Karelen), the land of the Karelian people, is an area in Northern Europe of historical significance for ...

. Krutov determined the significance of

chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...

in the development of contact-

metasomatic Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical com ...

deposits, which are found in the distribution of

amphiboles Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

scapolite The scapolites (Gr. σκάπος, rod, and λίθος, stone) are a group of rock-forming silicate minerals composed of aluminium, calcium, and sodium silicate with chlorine, carbonate and sulfate. The two endmembers are meionite () and marialit ...

, and

chlorapatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common en ...

. One of Krutov’s great achievements is a monograph: ''Ore Deposits of Cobalt'' which included cobalt and nickel ores in the Krusnehory Mountains and was published in 1959.

References

* Bayliss, P.; Stephenson, N.C. (1967) The Structure of gersdorffite. Mineralogical Magazine, pp. 38–41 * Hem, Skage R.; Makovicky, Emil (2004) The system Fe-Co-Ni-As-S; II, Phase relations in the (Fe,CO,Ni)As (sub 1.5) S (sub 0.5) section at 650 degrees and 500 degrees C., Canadian Mineralogist, Vol. 42, Part 1, pp. 63–86 * Ondruš, P.; Veselovský, F.; Gabašová, A.; Hloušek, J.; Šrein, V. (2003) Geology and hydrothermal vein system of the Jáchymov (Joachimsthal) ore district.

, Vol.48, Issue 3-4, pp 3–18 * Spiridonov, E. M.; Chvileva, T. N. (1996) The boundary between gersdorffite NiAsS and krutovite NiAs. Transactions Doklady of the Russian Academy of Sciences. Earth Science Sections, Vol. 344, Issue 7, pp. 119–123 * Veselovsky, Frantisek; Ondrus, Petr; Gabasova, Ananda; Hlousek, Jan; Vlasimsky, Pavel (2003) History of discovery and study of new primary minerals at Jachymov.

, Vol. 48, Issue 3-4, pp. 207–208 * Veselovský F.; Ondruš P; Gabašová A.; Hloušek J.; Vlašimský P.; Chernyshev IV (2003) Who was who in Jáchymov mineralogy II.:

, Vol 48, Issue 3-4, pp. 193 – 205 * Vinogradova, R. A.; Rudashevskiy, N. S.; Bud'ko, I. A.; Bochek, L. I.; Kaspar, P.; Padera, K. (1977) Krutovite, a new cubic nickel diarsenide. International Geology Review, Vol. 19, Issue 2, pp. 232–244 {{Commons, Krutovite Nickel minerals Arsenide minerals Pyrite group