Iron minerals

thumb|upright=1.3|Main tourmaline producing countries

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 hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.

Bornite, also known as peacock ore, is a sulfide mineral with chemical composition that crystallizes in the orthorhombic system (pseudo-cubic). It is an important copper ore.

Augite, also known as Augurite, is a common rock-forming pyroxene mineral with formula . The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees.

Arsenopyrite (IMA symbol: Apy) is an iron arsenic sulfide (FeAsS). It is a hard (Mohs 5.5–6) metallic, opaque, steel grey to silver white mineral with a relatively high relative density of 6.1.

Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks.

Pyrrhotite (pyrrhos in Greek meaning "flame-coloured") is an iron sulfide mineral with the formula Fe(1−x)S (x = 0 to 0.125). It is an iron-deficient nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is weakly magnetic. The magnetism decreases as the iron content increases, and troilite is non-magnetic. Pyrrhotite is generally tabular and brassy/bronze in color with a metallic luster. The mineral occurs with mafic igneous rocks like norites, and may form from pyrite during metamorp

Cobaltite is an arsenide and sulfide mineral with the mineral formula CoAsS. It is the naming mineral of the cobaltite group of minerals, whose members structurally resemble pyrite (FeS2).

thumb|Pentlandite in pyrrhotite, ore specimen from the [[Sudbury Basin (field of view 3.4 cm)|300x300px]] Pentlandite is an iron–nickel sulfide with the chemical formula . Pentlandite has a narrow variation range in nickel to iron ratios (Ni:Fe), but it is usually described as 1:1. In some cases, this ratio is skewed by the presence of pyrrhotite inclusions. It also contains minor cobalt, usually at low levels as a fraction of weight.

metamorphic rock

Fayalite (, commonly abbreviated to Fa) is the iron-rich end-member of the olivine solid-solution series. In common with all minerals in the olivine group, fayalite crystallizes in the orthorhombic system (space group Pbnm) with cell parameters a = 4.82 Å, b = 10.48 Å and c = 6.09 Å.

Wurtzite is a zinc and iron sulfide mineral with the chemical formula , a less frequently encountered structural polymorph form of sphalerite. The iron content is variable up to eight percent. It is trimorphous with matraite and sphalerite.

Tetrahedrite is a copper antimony sulfosalt mineral with the formula: . It is the antimony endmember of the continuous solid solution series with arsenic-bearing tennantite. Pure endmembers of the series are rarely if ever seen in nature. Of the two, the antimony rich phase is more common. Other elements also substitute in the structure, most notably iron and zinc, along with less common silver, mercury and lead. Bismuth also substitutes for the antimony site and bismuthian tetrahedrite or annivite is a recognized variety. The related, silver dominant, mineral species freibergite, although rar

volcano in Ethiopia

thumb|Pink eudialyte in syenite ([[lujavrite) from Poços de Caldas, Brazil. The white mineral is alkali feldspar, the black is aegirine, and the little brown bits are biotite.]]

Anthophyllite is an orthorhombic amphibole mineral: ☐Mg2Mg5Si8O22(OH)2 (☐ is for a vacancy, a point defect in the crystal structure), magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of anthophyllite are lamellar or fibrous and are classed as asbestos. The name is derived from the Latin word anthophyllum, meaning clove, an allusion to the most common color of the mineral. The Anthophyllite crystal is characterized by its perfect cleavage along directions 126 degrees and 54 degrees.

thumb|upright=1.0|Jules Bastien-Lepage, Pas Meche, 1882. An example of the shadows created by using umber in a painting.

The mineral group tantalite [(Fe, Mn)Ta2O6] is the primary source of the chemical element tantalum, a corrosion (heat and acid) resistant metal. It is chemically similar to columbite, and the two are often grouped together as a semi-singular mineral called coltan or "columbite-tantalite" in many mineral guides. However, tantalite has a much greater specific gravity than columbite (8.0+ compared to columbite's 5.2). Iron-rich tantalite is the mineral tantalite-(Fe) or ferrotantalite and manganese-rich is tantalite-(Mn) or manganotantalite.

Stannite is a mineral, a sulfide of copper, iron, and tin, in the category of thiostannates.

thumb|Scanning electron microscope|SEM image of Ringwoodite (RGW) discovered in the Suizhou L6 [[chondrite meteorite. See image for details. ]]

Kamacite is an alloy of iron and nickel, which is found on Earth only in meteorites. According to the International Mineralogical Association (IMA) it is considered a proper nickel-rich variety of the mineral native iron. The proportion iron:nickel is between 90%:10% and 95%:5%; small quantities of other elements, such as cobalt or carbon may also be present. The mineral has a metallic luster, is gray and has no clear cleavage although its crystal structure is isometric-hexoctahedral. Its density is about 8 g/cm3 and its hardness is 4 on the Mohs scale. It is also sometimes called balkene

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Loellingite, also spelled löllingite, is an iron arsenide mineral with formula FeAs2. It is often found associated with arsenopyrite (FeAsS) from which it is hard to distinguish. Cobalt, nickel and sulfur substitute in the structure. The orthorhombic lollingite group includes the nickel iron arsenide rammelsbergite and the cobalt iron arsenide safflorite. Leucopyrite is an old synonym for loellingite.

Germanite is a rare copper iron germanium sulfide mineral, Cu26Fe4Ge4S32. It was first discovered in 1922, and named for its germanium content. It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite. Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.

Sugilite ( ) is a relatively rare pink to purple cyclosilicate mineral with the complex chemical formula KNa2(Fe, Mn, Al)2Li3Si12O30. Sugilite crystallizes in the hexagonal system with prismatic crystals. The crystals are rarely found and the form is usually massive. It has a Mohs hardness of 5.5–6.5 and a specific gravity of 2.75–2.80. It is mostly translucent. Sugilite was first described in 1944 by the Japanese petrologist Ken-ichi Sugi (1901–1948) for an occurrence on Iwagi Islet, Japan, where it is found in an aegirine syenite intrusive stock. It is found in a similar environment at

thumb|right|200px|Widmanstätten pattern showing the two forms of Nickel-Iron, Kamacite and Taenite, in an octahedrite meteorite Taenite is a mineral found naturally on Earth mostly in iron meteorites. It is an alloy of iron and nickel, with a chemical formula of and nickel proportions of 20% up to 65%.

Chondrodite is a nesosilicate mineral with formula . Although it is a fairly rare mineral, it is the most frequently encountered member of the humite group of minerals. It is formed in hydrothermal deposits from locally metamorphosed dolomite. It is also found associated with skarn and serpentinite. It was discovered in 1817 at Pargas in Finland, and named from the Greek for "granule", which is a common habit for this mineral.

Saponite is a trioctahedral mineral of the smectite group. Its chemical formula is . It is soluble in sulfuric acid. It was first described in 1840 by Svanberg. Varieties of saponite are griffithite, bowlingite and sobotkite.

Cubanite is a copper iron sulfide mineral that commonly occurs as a minor alteration mineral in magmatic sulfide deposits. It has the chemical formula CuFe2S3 and when found, it has a bronze to brass-yellow appearance. On the Mohs hardness scale, cubanite falls between 3.5 and 4 and has a orthorhombic crystal system. Cubanite is chemically similar to chalcopyrite; however, it is the less common copper iron sulfide mineral due to crystallization requirements.

Beudandite is a secondary mineral occurring in the oxidized zones of polymetallic deposits. It is a lead, iron, arsenate, sulfate with endmember formula: PbFe3(OH)6SO4AsO4.

Schreibersite is generally a rare iron nickel phosphide mineral, , though common in iron-nickel meteorites. It has been found on Disko Island in Greenland and Illinois.

Safflorite is a rare cobalt iron arsenide mineral with the chemical formula . Pure safflorite is , but iron is virtually always present. Safflorite is a member of the three-way substitution series of arsenides known as the loellingite group. More than fifty percent iron makes the mineral loellingite whereas more than fifty percent nickel and the mineral is rammelsbergite. A parallel series of antimonide minerals exist.

Cohenite is a naturally occurring iron carbide mineral with the chemical structure (Fe, Ni, Co)3C. This forms a hard, shiny, silver mineral which was named by E. Weinschenk in 1889 after the German mineralogist Emil Cohen, who first described and analysed material from the Magura meteorite found near Slanica, Žilina Region, Slovakia. Cohenite is found in rod-like crystals in iron meteorites.

Aerinite () is a bluish-purple inosilicate mineral. It crystallizes in the monoclinic system and occurs as fibrous or compact masses and coatings. It has a dark, vitreous luster, a specific gravity of 2.48 and a Mohs hardness of 3.

Hercynite is a spinel mineral with the formula FeAl2O4.

Osumilite is a very rare potassium-sodium-iron-magnesium-aluminium silicate mineral. Osumilite is part of the milarite group (also known as the milarite-osumilite group) of cyclosilicates.

Glaucodot is a cobalt iron arsenic sulfide mineral with formula . The cobalt:iron(II) ratio is typically 3:1 with minor nickel substituting. It forms a series with arsenopyrite . It is an opaque grey to tin-white typically found as massive forms without external crystal form. It crystallizes in the orthorhombic system. The locality at Håkansboda, Sweden has rare twinned dipyramidal crystals (see photo). It is brittle with a Mohs hardness of 5 and a specific gravity of 5.95. It occurs in high temperature hydrothermal deposits with pyrrhotite and chalcopyrite. Glaucodot is classed as a sulfide i

Cerite is a complex silicate mineral group containing cerium, formula . The cerium and lanthanum content varies with the Ce rich species (cerite-(Ce)) and the La rich species (cerite-(La)). Analysis of a sample from the Mountain Pass carbonatite gave 35.05% and 30.04% .

Aeschynite-(Y) (or Aeschinite-(Y), Aeschynite-(Yt), Blomstrandine, Priorite) is a rare earth mineral of yttrium, calcium, iron, thorium, titanium, niobium, oxygen, and hydrogen with the chemical formula . Its name comes from the Greek word for "shame". Its Mohs scale rating is 5 to 6.

Corkite is a phosphate mineral in the beudantite subgroup of the alunite group. Corkite is the phosphate analogue of beudantite and with it, a complete solid solution range exists. Corkite will also form a solid solution with kintoreite.

Zhemchuzhnikovite is an oxalate mineral of organic origin; formula NaMg(FeAl)C2O4·8H2O. It forms smoky green crystals with a vitreous lustre and is found in Russian coal mines. It is named after Yury Zhemchuzhnikov (1885–1957), a Russian clay mineralogist.

Ludlamite is a rare phosphate mineral with chemical formula . It was first described in 1877 for an occurrence in Wheal Jane mine in Cornwall, England and named for English mineralogist Henry Ludlam (1824–1880).

Orthorhombic ferroselite and its isometric polymorph dzharkenite are iron selenides of general formula FeSe2 precipitated under reducing conditions in anoxic environments. They are a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits.

Chapmanite is a rare silicate mineral belonging to the phyllosilicate group, discovered in 1924, and named in honour of the late Edward John Chapman (1821–1904), a geology professor at the University of Toronto. Chemically, it is an iron antimony silicate, closely related to bismutoferrite, and may contain aluminium impurities. It is closely associated with silver mines, most notably the Keeley mine in Ontario, Canada, found in quartz veinlets containing graphite in gneiss. It takes the form of a powdery, yellow-green, semitransparent solid, and leaves a streak of the same color. Early German

Freibergite is a complex sulfosalt mineral of silver, copper, iron, antimony and arsenic with formula . It has cubic crystals and is formed in hydrothermal deposits. It forms one solid solution series with tetrahedrite and another with argentotennantite. Freibergite is an opaque, metallic steel grey to black and leaves a reddish-black streak. It has a Mohs hardness of 3.5 to 4.0 and a specific gravity of 4.85 to 5. It is typically massive to granular in habit with no cleavage and an irregular fracture.

Cylindrite is a sulfosalt mineral containing tin, lead, antimony and iron with formula: Pb3Sn4FeSb2S14. It forms triclinic pinacoidal crystals which often occur as tubes or cylinders which are in fact rolled sheets. It has a black to lead grey metallic colour with a Mohs hardness of 2 to 3 and a specific gravity of 5.4.

Talnakhite is a mineral of chalcopyrite group with formula: Cu9(Fe, Ni)8S16. 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 "talnakhite" in 1968. Despite the initial announcement it turned out to be not a face centered high-temperature polymorph of chalcopyrite, but to have composition Cu18(Fe, Ni)18S32. At to it decomposes to tetragonal cubanite plus bornite.

Niningerite is a magnesium–iron–manganese sulfide mineral with the chemical formula MgS that is found in enstatite chondrite meteorites. Niningerite is the magnesium-dominant analog of keilite. This mineral is named after Harvey H. Nininger.

Allabogdanite is a very rare phosphide mineral with the chemical formula , found in 1994 in a meteorite. It was described for an occurrence in the Onello meteorite in the Onello River basin, Sakha Republic; Yakutia, Russia; associated with taenite, schreibersite, kamacite, graphite and awaruite. It was named for Russian geologist Alla Bogdanova.

Delvauxite, also known as borickite, is a yellow to brown to dark brown amorphous mineral, sometimes forming a botryoidal mass. Its chemical formula is . and it may sometimes form stalactites.

Rodalquilarite is a rare iron tellurite chloride mineral with formula H3Fe3+2(Te4+O3)4Cl or Fe2(TeO2OH)3(TeO3)Cl. Rodalquilarite crystallizes in the triclinic system and typically occurs as stout green prisms and encrustations.

Icosahedrite is the first known naturally occurring quasicrystal phase. It has the composition Al63Cu24Fe13 and is a mineral approved by the International Mineralogical Association in 2010. Its discovery followed a 10-year-long systematic search by an international team of scientists led by Luca Bindi and Paul J. Steinhardt to find the first natural quasicrystal.

Haxonite is an iron nickel carbide mineral found in iron meteorites and carbonaceous chondrites. It has a chemical formula of , crystallises in the cubic crystal system and has a Mohs hardness of - 6.

Valleriite is an uncommon sulfide mineral (hydroxysulfide) of iron and copper with formula: or . It is an opaque, soft, bronze-yellow to brown mineral which occurs as nodules or encrustations.

Villamanínite is a copper sulfide mineral with small amounts of other elements, belonging to group II according to the Strunz classification. It was discovered in 1920 when studying the copper minerals of the Providencia mine in the municipality of Cármenes, León (Spain). The English researchers who identified it gave it the name of villamaninite when they confused the municipality in which the mine was actually located, because Villamanín is where the ore was loaded onto the railroad for export.

Szomolnokite (Fe2+SO4·H2O) is a monoclinic iron sulfate mineral forming a complete solid solution with magnesium end-member kieserite (MgSO4·H2O). In 1877 szomolnokite's name was derived by Joseph Krenner from its type locality of oxidized sulfide ore containing iron in Szomolnok, Slovakia (Hungary at the time).

thumb|Smaltite - Schneeberg Germany

Kidwellite in an uncommon mineral that was discovered in Arkansas in the United States. It was approved by the IMA in 1974, but it was only named in 1978 by Moore and Ito after Albert Lewis (Laws) Kidwell.

Fukuchilite, , is a copper iron sulfide named after the Japanese mineralogist Nobuyo Fukuchi (1877–1934), that occurs in ore bodies of gypsum-anhydrite at the intersection points of small masses of barite, covellite, gypsum and pyrite, and is mostly found in the Hanawa mine in the Akita prefecture of Honshū, Japan where it was first discovered in 1969. It occurs in masses within the third geologic unit of the Kuroko type deposits within the mine.

Frohbergite (, title by proper name: Max Hans Frohberg), also iron telluride is a rare hydrothermal mineral from the sulfide class, in composition — iron telluride with the ideal formula FeTe2 (contains 82.05% tellurium and 17.95% iron).