Krutovite is a

cubic Cubic may refer to: Science and mathematics * Cube (algebra), "cubic" measurement * Cube, a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex ** Cubic crystal system, a crystal system w ...

nickel Nickel is a chemical element; it has 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 slo ...

diarsenide with a chemical composition of NiAs₂ and a

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

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

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

with trace to minor amounts of

cobalt Cobalt is a chemical element; it has Symbol (chemistry), 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. ...

iron Iron is a chemical element; it has symbol Fe () 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, forming much of Earth's o ...

copper Copper is a chemical element; it has symbol Cu (from Latin ) 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 pinkish-orang ...

, sulfur, and

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

.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 (; 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. Jáchymov has a long mining tradition, thanks to which it used to be the second most popu ...

Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...

, in the

Ore Mountains The Ore Mountains (, or ; ) lie along the Czech–German border, separating the historical regions of Bohemia in the Czech Republic and Saxony in Germany. The highest peaks are the Klínovec in the Czech Republic (German: ''Keilberg'') at ab ...

.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 The Ore Mountains are composed of two parts: the

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 t ...

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, caus ...

s and the Lower

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

metamorphic

volcano A volcano is commonly defined as a vent or fissure 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 oft ...

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

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 Potůčky ore district where krutovite was originally found lies on the northern fault zone. Heading south is the Ore Mountains

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 f ...

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 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 fetal c ...

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 (phanerite, phaneritic) intrusive rock, 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 coo ...

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

strike and dip In geology, strike and dip is a measurement convention used to describe the plane orientation or Attitude (geometry), attitude of a Plane (geometry), planar Geology, geologic feature. A feature's strike is the azimuth of an imagined horizontal ...

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 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 subscript of 2–3. High nickel varieties are refe ...

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, tetrahed ...

. 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 The term ''isometric'' comes from the Greek for "having equal measurement". isometric may mean: * Cubic crystal system, also called isometric crystal system * Isometre, a rhythmic technique in music. * "Isometric (Intro)", a song by Madeon from ...

-dipoloidal system (2/m) and is known to have the same structure type as

gersdorffite Gersdorffite or ''Nickel glance'' (trivial name) 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 w ...

type P2₁3. Krutovite and gersdorffite form a

solid solution A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solutio ...

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 (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 tertiary education, post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin ...

of mineralogy of

Moscow University Moscow State University (MSU), officially M. V. Lomonosov Moscow State University,. is a public research university in Moscow, Russia. The university includes 15 research institutes, 43 faculties, more than 300 departments, and six branches. Al ...

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 ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.

and

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

; 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 usua ...

massif A massif () is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits (e.g. France's Massif Central). In mountaineering literature, ''massif'' is frequently used to denote the main mass of an ...

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

Norilsk Norilsk ( rus, Нори́льск, p=nɐˈrʲilʲsk) is a closed city in Krasnoyarsk Krai, Russia, located south of the western Taymyr Peninsula, around 90 km east of the Yenisei, Yenisey River and 1,500 km north of Krasnoyarsk. Norilsk is 300 ...

in the Kranoyarsk region and Monchegorsk in

Karelia Karelia (; Karelian language, Karelian and ; , historically Коре́ла, ''Korela'' []; ) is an area in Northern Europe of historical significance for Russia (including the Soviet Union, Soviet era), Finland, and Sweden. It is currentl ...

. Krutov determined the significance of

chlorine Chlorine is a chemical element; it has 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 between ...

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 traditionally defined as metamorphism which involves a change in the 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 ...

scapolite The scapolites (, "rod", and , "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 marialite (). Silvialite i ...

, and

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

. 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

NiAsS and krutovite NiAs₂. 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 Nickel minerals Arsenide minerals Pyrite group