Krutovite
Encyclopedia
Krutovite is a cubic
nickel
diarsenide
with a chemical composition of NiAs2 and a sulfur
content of 0.02-0.34 weight percent (Vinogradova, et al., 1977). Krutovite is composed of nickel and arsenic
with trace to minor amounts of cobalt
, iron
, copper
, sulfur, and antimony
(Vinogradova, et al., 1977).
(Veselovsky, et al., 2003). Jáchymov, is a 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
metamorphic rock
s and the Lower Paleozoic
metamorphic volcano
sedimentary sequence (Ondruš, et al., 2003). 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 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
come from the major fault lines where krutovite crystallized at moderate hydrothermal 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 (Ondruš, et al., 2003). Krutovite comes from the midnight vein in the Svornmost mine which contains nickel ores as deep as 100 meters in the granite
body. The midnight veins are known to exhibit frequent variations in their strike and dip
and have an average width of 10-30 cm. (Ondruš, et al., 2003). 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
and sometimes with tennantite
. When this occurs the intergrowth is smooth and there is no visible reaction (Spiridonov, et al., 1996).
type P213 (Spiridonov, et al., 1996). Krutovite and gersdorffite form a solid solution
at a temperature of less than 300 °C.
crystal system
(3bar 2/m) and space group Pa3 (Barthelmy, et al., 2005). Krutovite is opaque grayish white paler then the color of nickel skutterudite
. 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. (Vinogradova, et al., 1977). Krutovite has high degree of reflectance about 64.0-67.0% higher than known nickel arsenides and sulfarsenides (Vinogradova, et al., 1977). 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 (Vinogradova, et al., 1977).
of mineralogy of Moscow University 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
and Kazakhstan
; cobalt in Dashkesan deposit, nickel in silicate ores in ultramafic massif
s of the Southern Ural, the Cu-Ni (Co) deposits of Norilsk
in the Kranoyarsk region and Monchegorsk in Karelia
(Veselovsky, et al., 2003). Krutov devised the significant of chlorine
in the development of contact-metasomatic deposits, which are found in the distribution of amphiboles, scapolite
, and chlorapatite. 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 (Veselovsky, et al., 2003).
Cubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
diarsenide
Arsenide
Arsenide is an arsenic anion with the charge −3. The trianion is formed by the reduction of arsenic by three electrons. For example heating arsenic powder with excess sodium gives sodium arsenide . The anions have no existence in solution since they are extremely basic...
with a chemical composition of NiAs2 and a sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
content of 0.02-0.34 weight percent (Vinogradova, et al., 1977). Krutovite is composed of nickel and arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
with trace to minor amounts of cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, sulfur, and antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
(Vinogradova, et al., 1977).
Geological occurrence
Krutovite occurs in the Geshiber vein, Svornost shaft, 8th level, in the northwest strike of JáchymovJáchymov
For other places called Joachimsthal, see Joachimsthal Jáchymov . compl: "Sant Joachim's Sthal" is a spa town in north-west Bohemia in the Czech Republic belonging to the Karlovy Vary Region. It is situated at an altitude of 733 m above sea level in the eponymous St...
(Veselovsky, et al., 2003). Jáchymov, is a Czech
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
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
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
s and the Lower Paleozoic
Paleozoic
The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...
metamorphic volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
sedimentary sequence (Ondruš, et al., 2003). 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 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
Vein (geology)
In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation...
come from the major fault lines where krutovite crystallized at moderate hydrothermal 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 (Ondruš, et al., 2003). Krutovite comes from the midnight vein in the Svornmost mine which contains nickel ores as deep as 100 meters in the granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
body. The midnight veins are known to exhibit frequent variations in their strike and dip
Strike and dip
Strike and dip refer to the orientation or attitude of a geologic feature. The strike line of a bed, fault, or other planar feature is a line representing the intersection of that feature with a horizontal plane. On a geologic map, this is represented with a short straight line segment oriented...
and have an average width of 10-30 cm. (Ondruš, et al., 2003). 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
Skutterudite is a cobalt arsenide mineral that has variable amounts of nickel and iron substituting for cobalt with a general formula: As3. Some references give the arsenic a variable formula subscript of 2-3. High nickel varieties are referred to as nickel-skutterudite, previously chloanthite...
and sometimes with tennantite
Tennantite
Tennantite is a copper arsenic sulfosalt mineral. Its chemical formula is Cu12As4S13. It is grey-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedrite has antimony substituting for arsenic and the two form a solid solution series. The two have very similar...
. When this occurs the intergrowth is smooth and there is no visible reaction (Spiridonov, et al., 1996).
Structure
Krutovite is from the family of the isometric-dipoloidal system (3bar2/m) and is known to have the same structure type as gersdorffiteGersdorffite
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 a solid solution series with cobaltite, CoAsS....
type P213 (Spiridonov, et al., 1996). Krutovite and gersdorffite form a solid solution
Solid solution
A solid solution is a solid-state solution of one or more solutes in a solvent. Such a mixture is considered a solution rather than a compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase...
at a temperature of less than 300 °C.
Physical properties
Krutovite is affiliated with the isometric-dipoloidalCubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
crystal system
Crystal system
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals...
(3bar 2/m) and space group Pa3 (Barthelmy, et al., 2005). Krutovite is opaque grayish white paler then the color of nickel skutterudite
Skutterudite
Skutterudite is a cobalt arsenide mineral that has variable amounts of nickel and iron substituting for cobalt with a general formula: As3. Some references give the arsenic a variable formula subscript of 2-3. High nickel varieties are referred to as nickel-skutterudite, previously chloanthite...
. 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. (Vinogradova, et al., 1977). Krutovite has high degree of reflectance about 64.0-67.0% higher than known nickel arsenides and sulfarsenides (Vinogradova, et al., 1977). 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 (Vinogradova, et al., 1977).
Biographic sketch
Kruotvite was named in honor of Georgi Alekseyevich Krutov (24 April 1902 - 11 December 1989) who was a professorProfessor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
of mineralogy of Moscow University 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
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...
and Kazakhstan
Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
; cobalt in Dashkesan deposit, nickel in silicate ores in ultramafic massif
Massif
In geology, a massif 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...
s of the Southern Ural, the Cu-Ni (Co) deposits of Norilsk
Norilsk
Norilsk is an industrial city in Krasnoyarsk Krai, Russia, located between the Yenisei River and the Taymyr Peninsula. Population: It was granted city status in 1953. It is the northernmost city in Siberia and the world's second largest city north of the Arctic Circle...
in the Kranoyarsk region and Monchegorsk in Karelia
Karelia
Karelia , the land of the Karelian peoples, is an area in Northern Europe of historical significance for Finland, Russia, and Sweden...
(Veselovsky, et al., 2003). Krutov devised the significant of chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
in the development of contact-metasomatic deposits, which are found in the distribution of amphiboles, scapolite
Scapolite
Scapolite , is a group of rock-forming silicate minerals composed of aluminium, calcium, and sodium silicate with chlorine, carbonate and sulfate.-Properties:...
, and chlorapatite. 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 (Veselovsky, et al., 2003).