Mooihoekite is a 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...

 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...

 sulfide mineral

Sulfide mineral

The sulfide minerals are a class of minerals containing sulfide as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts...

 with chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 of Cu₉Fe₉S₁₆. The mineral was discovered in 1972 and received its name from its discovery area, the Mooihoek mine in Transvaal

Transvaal Province

Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...

, South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

.

Crystal structure and optical properties

Mooihoekite crystallizes in the tetragonal 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...

. It has a short optical c-axis that is perpendicular to two longer a-axes of equal length. For Mooihoekite, the c-axis is a 4-fold rotoinversion axis.

Mooihoekite is an opaque mineral which shows weak anisotropism in polished section under reflected light microscopy. It goes slightly extinct every 90°.

Occurrence

It is found in massive sulfide from pipe-shaped dunite

Dunite

Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse-grained or phaneritic texture. The mineral assemblage is greater than 90% olivine, with minor amounts of other minerals such as pyroxene, chromite and pyrope. Dunite is the olivine-rich end-member of the peridotite group...

 pegmatite

Pegmatite

A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic....

 in the norite

Norite

Norite is a mafic intrusive igneous rock composed largely of the calcium-rich plagioclase labradorite and hypersthene with olivine. Norite is essentially indistinguishable from gabbro without thin section study under the petrographic microscope...

 zone of the Bushveld igneous complex

Bushveld igneous complex

The Bushveld Igneous Complex is a large layered igneous intrusion within the Earth's crust which has been tilted and eroded and now outcrops around what appears to be the edge of a great geological basin, the Transvaal Basin. Located in South Africa, the BIC contains some of the richest ore...

 in South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

. It has also been found in troctolite

Troctolite

Troctolite is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with variable minor pyroxene. It is an olivine-rich, pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a...

 from the basal Duluth gabbro in Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

, USA; in the Talnakh area, 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...

 region, western Siberia

Siberia

Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

; at
Krzemianka

Krzemianka

Krzemianka is a village in the administrative district of Gmina Jeleniewo, within Suwałki County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately west of Jeleniewo, north of Suwałki, and north of the regional capital Białystok....

, Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

; in the Malanjkhand

Malanjkhand

Malanjkhand is an open-pit copper mine in India. Located near the town of Malaj Khand, northeast of Balaghat in Madhya Pradesh, at an altitude of 576 MRL. It falls in the tehsil of Baihar, which is from the project, on the way to , Balaghat, Madhya Pradesh State. It is the largest base metal...

 copper-molybdenum deposit, Madhya Pradesh

Madhya Pradesh

Madhya Pradesh , often called the Heart of India, is a state in central India. Its capital is Bhopal and Indore is the largest city....

, India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

; and the Stillwater igneous complex

Stillwater igneous complex

The Stillwater igneous complex is a large layered intrusion located in southern Montana in Stillwater, Sweet Grass and Park Counties. The complex is exposed across 30 miles of the north flank of the Beartooth Mountain Range. The complex has extensive reserves of chromium ore and has a history of...

 in Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

, USA.

Mooihoekite occurs in association with haycockite, magnetite

Magnetite

Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...

, troilite

Troilite

Troilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron rich endmember of the pyrrhotite group. Pyrrhotite has the formula FeS which is iron deficient...

, cuprian pentlandite

Pentlandite

Pentlandite is an iron-nickel sulfide, 9S8. Pentlandite usually has a Ni:Fe ratio of close to 1:1. It also contains minor cobalt.Pentlandite forms isometric crystals, but is normally found in massive granular aggregates. It is brittle with a hardness of 3.5 - 4 and specific gravity of 4.6 - 5.0 and...

, mackinawite

Mackinawite

Mackinawite is an iron nickel sulfide mineral with formula 1 + xS . It crystallizes in the tetragonal crystal system and occurs as opaque bronze to grey-white tabular crystals and anhedral masses. It has a Mohs hardness of 2.5 and a specific gravity of 4.17.-Occurrence:It occurs in serpentinized...

, sphalerite

Sphalerite

Sphalerite is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides...

, and moncheite in the Mooihoek mine and with haycockite, native copper

Native copper

Copper, as native copper, is one of the few metallic elements to occur in uncombined form as a natural mineral, although most commonly occurs in oxidized states and mixed with other elements...

, troilite, pentlandite, cubanite

Cubanite

Cubanite is a yellow mineral of copper, iron, and sulfur, CuFe2S3.Cubanite was first described in 1843 for an occurrence in the Mayarí-Baracoa Belt, Oriente Province, Cuba....

 and magnetite in the Duluth complex.

Uses

Mooihoekite is a rare mineral that is mostly used for research purposes. It has similar properties to chalcopyrite

Chalcopyrite

Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...

 CuFeS₂, making it helpful in the study of ore deposits and the study of the central portion of the Cu-Fe-S phase system. Mooihoekite, chalcopyrite, talnakhite

Talnakhite

Talnakhite is a mineral of chalcopyrite group with formula: Cu98S16. It occurs in olivinic gabbro-dolerite. It was named after the Talnakh ore deposit, near Norilsk in Western Siberia, Russia where it was discovered as reported in 1963 by I. Budko and E. Kulagov. It was officially named...

, and haycockite all play key roles in the study of ore genesis

Ore genesis

The various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. Ore genesis theories are very dependent on the mineral or commodity....

 and beneficiation

Beneficiation

In mining, beneficiation is a variety of processes whereby extracted ore from mining is separated into mineral and gangue, the former suitable for further processing or direct use....

.