magnetite
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Magnetite is a
mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the proces ...

mineral
and one of the main
iron ore Iron ores are rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the way in which it is formed. Rock ...
s, with the chemical formula Fe3O4. It is one of the
oxides of iron
oxides of iron
, and is
ferrimagnetic A Ferrimagnetic material is material that has populations of atoms with opposing magnetic moment The magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field A magnetic field is ...
; it is attracted to a
magnet A magnet is a material or object that produces a . This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other s, such as , , , , etc. and attracts or repels other magnets. A p ...

magnet
and can be magnetized to become a
permanent magnet Magnetic field lines of a solenoid electromagnet, which are similar to a bar magnet as illustrated below with the iron filings A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsi ...
itself. It is the most
magnetic Magnetism is a class of physical attributes that are mediated by s. s and the s of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomenon of . The ...

magnetic
of all the naturally occurring minerals on Earth. Naturally magnetized pieces of magnetite, called
lodestone of the Smithsonian Image:Lodestone (black).jpg, Lodestone attracting small bits of iron A lodestone is a naturally magnetized piece of the mineral magnetite Magnetite is a mineral and one of the main iron ore Iron ores are rocks and min ...
, will attract small pieces of iron, which is how ancient peoples first discovered the property of
magnetism Magnetism is a class of physical attributes that are mediated by magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge i ...

magnetism
. Magnetite is black or brownish-black with a metallic luster, has a
Mohs hardness The Mohs scale of mineral hardness () is a Qualitative property, qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was creat ...
of 5–6 and leaves a black streak. Small grains of magnetite are very common in
igneous Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the p ...

igneous
and metamorphic rocks. The chemical
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science Council (ISC). IUPAC ...
name is
iron(II,III) oxide Iron(II,III) oxide is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite Magnetite is a mineral and one of the main iron ore Iron ores are rocks and minerals from which metal A metal (from Ancient Gr ...
and the common chemical name is ''ferrous-ferric oxide''.


Properties

In addition to igneous rocks, magnetite also occurs in
sedimentary rocks Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth scien ...
, including
banded iron formation showing banded iron formation, displayed in Dresden, Saxony, Germany Banded iron formations (also known as banded ironstone formations or BIFs) are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iro ...

banded iron formation
s and in lake and marine sediments as both detrital grains and as
magnetofossils Magnetofossils are the fossil A fossil (from Classical Latin: , literally "obtained by digging") is any preserved remains, impression, or trace of any once- living thing from a past geological age. Examples include bones, shells, exoskel ...
. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to
maghemite Maghemite (Fe2O3, γ-Fe2O3) is a member of the family of iron oxides. It has the same spinel ferrite structure as magnetite Magnetite is a mineral and one of the main iron ore Iron ores are rocks and minerals from which metal A metal ...
.


Crystal structure

The chemical composition of magnetite is Fe2+(Fe3+)2(O2-)4. This indicates that magnetite contains both ferrous (
divalent In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they und ...
) and ferric (
trivalent In chemistry, the valence or valency of an chemical element, element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of an atom of a given ...

trivalent
) iron, suggesting crystallization in an environment containing intermediate levels of oxygen. The main details of its structure were established in 1915. It was one of the first crystal structures to be obtained using
X-ray diffraction X-ray crystallography (XRC) is the experimental science determining the atomic and molecular structure of a crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a ...
. The structure is inverse
spinel Spinel () is the magnesium Magnesium is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only o ...
, with O2− ions forming a
face-centered cubic 200px, A network model of a primitive cubic system In crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids (see crystal structure). The word "crystallography" is derived fro ...

face-centered cubic
lattice and iron cations occupying interstitial sites. Half of the Fe3+ cations occupy tetrahedral sites while the other half, along with Fe2+ cations, occupy octahedral sites. The unit cell consists of 32O2− ions and unit cell length is ''a'' = 0.839 nm. As a member of the inverse spinel group, magnetite can form
solid solution A solid solution describes a family of materials which have a range of compositions (e.g. AxB1−x) and a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to desc ...

solid solution
s with similarly structured minerals, including ulvospinel () and
magnesioferrite Magnesioferrite is a magnesium iron oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titanium and titanium forms six bonds to oxygen. An oxide () is a chemical compound that contains at lea ...

magnesioferrite
(). Titanomagnetite, also known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many
mafic A mafic mineral or rock is a silicate mineral Silicate minerals are rock-forming mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science c ...
igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite.


Crystal morphology and size

Natural and synthetic magnetite occurs most commonly as
octahedral In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space ...

octahedral
crystals bounded by planes and as . Twinning occurs on the plane. Hydrothermal synthesis usually produces single octahedral crystals which can be as large as across. In the presence of mineralizers such as 0.1M HI or 2M and at 0.207
MPa The pascal (symbol: Pa) is the SI derived unit SI derived units are units of measurement ' Measurement is the number, numerical quantification (science), quantification of the variable and attribute (research), attributes of an object or event, ...
at 416–800 °C, magnetite grew as crystals whose shapes were a combination of rhombic-dodechahedra forms. The crystals were more rounded than usual. The appearance of higher forms was considered as a result from a decrease in the surface energies caused by the lower surface to volume ratio in the rounded crystals.


Reactions

Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce
hematite Hematite (), also spelled as haematite, is a common iron oxide Iron oxides are chemical compounds composed of iron and oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member o ...

hematite
, and the mineral pair forms a
buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * M ...
that can control how oxidizing its environment is (the
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
fugacity In chemical thermodynamics, the fugacity of a real gas is an effective partial pressure which replaces the mechanical partial pressure in an accurate computation of the chemical equilibrium constant. It is equal to the pressure of an ideal gas w ...
). This buffer is known as the hematite-magnetite or HM buffer. At lower oxygen levels, magnetite can form a buffer with
quartz Quartz is a hard, crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together an ...

quartz
and
fayalite Fayalite (Fe2SiO4; commonly abbreviated to Fa) is the iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and gro ...

fayalite
known as the QFM buffer. At still lower oxygen levels, magnetite forms a buffer with
wüstite Wüstite (FeO) is a mineral form of iron(II) oxide Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite.https://www.mindat.org/min-4316.htmlhttps://www.ima-mineralogy.org/Minlis ...
known as the MW buffer. The QFM and MW buffers have been used extensively in laboratory experiments on rock chemistry. The QFM buffer, in particular, produces an oxygen fugacity close to that of most igneous rocks. Commonly,
igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock is ...
s contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite. Compositions of the mineral pairs are used to calculate oxygen fugacity: a range of oxidizing conditions are found in magmas and the oxidation state helps to determine how the magmas might evolve by fractional crystallization. Magnetite also is produced from
peridotite Peridotite ( ) is a dense, coarse-grained igneous rock Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spok ...
s and
dunite Dunite (), also known as olivinite (not to be confused with the mineral olivenite Olivenite is a copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, ...
s by
serpentinization File:Folded serpentinite.jpg, Tightly folded serpentinite from the Tux Alps, Austria. Closeup view about . Serpentinite is a Rock (geology), rock composed of one or more serpentine group minerals, the name originating from the similarity of th ...

serpentinization
.


Magnetic properties

Lodestones were used as an early form of
magnetic compass A compass is a magnetometer that shows the geographic cardinal direction The four cardinal directions, or cardinal points, are the directions north North is one of the four compass points or cardinal directions. It is the opposite of ...
. Magnetite has been a critical tool in
paleomagnetism Paleomagnetism, American and British English spelling differences#ae and oe, or palaeomagnetism, is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Magnetic minerals in rocks can lock-in a re ...
, a science important in understanding
plate tectonics upright=1.35, Diagram of the internal layering of Earth showing the lithosphere above the asthenosphere (not to scale) Plate tectonics (from the la, label=Late Latin Late Latin ( la, Latinitas serior) is the scholarly name for the written L ...
and as historic data for
magnetohydrodynamics Magnetohydrodynamics (MHD; also magneto-fluid dynamics or hydro­magnetics) is the study of the magnetic properties and behaviour of electrically conducting fluid In physics, a fluid is a substance that continually Deformation (mechanics ...
and other
scientific fields The branches of science, also referred to as sciences, "scientific fields", or "scientific disciplines," are commonly divided into three major groups: *Formal sciences: the study of formal systems, such as those under the branches of logic an ...
. The relationships between magnetite and other iron oxide minerals such as
ilmenite Crystal structure of ilmenite Ilmenite, also known as manaccanite, is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. From a commercial perspective, ilmenite is the most important o ...
, hematite, and ulvospinel have been much studied; the
reaction Reaction may refer to a process or to a response to an action, event, or exposure: Physics and chemistry *Chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformat ...
s between these minerals and
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
influence how and when magnetite preserves a record of the
Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field A magnetic field is a vector field In vector calculus and physics, a vector field is an assignment of a vector to each point in a subset of space. Fo ...
. At low temperatures, magnetite undergoes a crystal structure phase transition from a monoclinic structure to a cubic structure known as the Verwey transition. Optical studies show that this metal to insulator transition is sharp and occurs around 120K. The Verwey transition is dependent on grain size, domain state, pressure, and the iron-oxygen
stoichiometry Stoichiometry refers to the relationship between the quantities of reactant 200px, Reactants, such as sulfur (''pictured''), are the starting materials that are used in chemical reactions. A reagent is a substance or compound added to a sy ...
. An isotropic point also occurs near the Verwey transition around 130K, at which point the sign of the magnetocrystalline anisotropy constant changes from positive to negative. The
Curie temperature In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throug ...
of magnetite is . If magnetite is in a large enough quantity it can be found in
aeromagnetic survey An aeromagnetic survey is a common type of geophysical survey Geophysical survey is the systematic collection of geophysical data for spatial studies. Detection and analysis of the geophysical signals forms the core of Geophysical signal process ...
s using a magnetometer which measures magnetic intensities.


Distribution of deposits

Magnetite is sometimes found in large quantities in beach sand. Such black sands (mineral sands or iron sands) are found in various places, such as Lung Kwu Tan of Hong Kong; California, United States; and the west coast of the North Island of New Zealand. The magnetite, eroded from rocks, is carried to the beach by rivers and concentrated by wave action and currents. Huge deposits have been found in banded iron formations. These sedimentary rocks have been used to infer changes in the oxygen content of the atmosphere of the Earth. Large deposits of magnetite are also found in the Atacama region of Chile (Chilean Iron Belt); the Valentines region of Uruguay; Kiruna, Sweden; the Tallawang, New South Wales, Tallawang Region of New South Wales; and in the Adirondack Mountains, Adirondack region of New York (state), New York in the United States. Kediet ej Jill, the highest mountain of Mauritania, is made entirely of the mineral. Deposits are also found in Norway, Romania, and the Ukraine. Magnetite-rich sand dunes are found in southern Peru. In 2005, an exploration company, Cardero Resources, discovered a vast deposit of magnetite-bearing sand dunes in Peru. The dune field covers 250 square kilometers (100 sq mi), with the highest dune at over 2,000 meters (6,560 ft) above the desert floor. The sand contains 10% magnetite. In large enough quantities magnetite can affect compass navigation. In Tasmania there are many areas with highly magnetized rocks that can greatly influence compasses. Extra steps and repeated observations are required when using a compass in Tasmania to keep navigation problems to the minimum. Magnetite crystals with a cube, cubic habit are rare but have been found at Balmat, St. Lawrence County, New York, and at Långban, Långban, Sweden. This habit may be a result of crystallization in the presence of cations such as zinc. Magnetite can also be found in fossils due to biomineralization and are referred to as magnetofossils. There are also instances of magnetite with origins in Outer space, space coming from meteorites.


Biological occurrences

Biomagnetism is usually related to the presence of biogenic crystals of magnetite, which occur widely in organisms. These organisms range from magnetotactic bacteria (e.g., ''Magnetospirillum magnetotacticum'') to animals, including humans, where magnetite crystals (and other magnetically sensitive compounds) are found in different organs, depending on the species. Biomagnetites account for the effects of weak magnetic fields on biological systems. There is also a chemical basis for cellular sensitivity to electric and magnetic fields (galvanotaxis). Pure magnetite particles are Biomineralization, biomineralized in magnetosomes, which are produced by several species of magnetotactic bacteria. Magnetosomes consist of long chains of oriented magnetite particle that are used by bacteria for navigation. After the death of these bacteria, the magnetite particles in magnetosomes may be preserved in sediments as magnetofossils. Some types of Anaerobic organism, anaerobic bacteria that are not magnetotactic can also create magnetite in oxygen free sediments by reducing amorphic ferric oxide to magnetite. Several species of birds are known to incorporate magnetite crystals in the upper beak for magnetoreception, which (in conjunction with cryptochromes in the retina) gives them the ability to sense the direction, Magnetic polarity, polarity, and magnitude of the ambient magnetic field. Chitons, a type of mollusk, have a tongue-like structure known as a radula, covered with magnetite-coated teeth, or Dermal denticle, denticles. The hardness of the magnetite helps in breaking down food. Biological magnetite may store information about the magnetic fields the organism was exposed to, potentially allowing scientists to learn about the migration of the organism or about changes in the Earth's magnetic field over time.


Human brain

Living organisms can produce magnetite. In humans, magnetite can be found in various parts of the brain including the frontal, parietal, occipital, and temporal lobes, brainstem, cerebellum and basal ganglia.Magnetite Nano-Particles in Information Processing: From the Bacteria to the Human Brain Neocortex - Iron can be found in three forms in the brain – magnetite, hemoglobin (blood) and ferritin (protein), and areas of the brain related to motor function generally contain more iron. Magnetite can be found in the hippocampus. The hippocampus is associated with information processing, specifically learning and memory. However, magnetite can have toxic effects due to its charge or magnetic nature and its involvement in oxidative stress or the production of free radicals. Research suggests that beta-amyloid plaques and tau proteins associated with neurodegenerative disease frequently occur after oxidative stress and the build-up of iron. Some researchers also suggest that humans possess a magnetic sense, proposing that this could allow certain people to use magnetoreception for navigation. The role of magnetite in the brain is still not well understood, and there has been a general lag in applying more modern, interdisciplinary techniques to the study of biomagnetism. Electron microscope scans of human brain-tissue samples are able to differentiate between magnetite produced by the body's own cells and magnetite absorbed from airborne pollution, the natural forms being jagged and crystalline, while magnetite pollution occurs as rounded nanoparticles. Potentially a human health hazard, airborne magnetite is a result of pollution (specifically combustion). These nanoparticles can travel to the brain via the olfactory nerve, increasing the concentration of magnetite in the brain. In some brain samples, the nanoparticle pollution outnumbers the natural particles by as much as 100:1, and such pollution-borne magnetite particles may be linked to abnormal neural deterioration. In one study, the characteristic nanoparticles were found in the brains of 37 people: 29 of these, aged 3 to 85, had lived and died in Mexico City, a significant air pollution hotspot. Some of the further eight, aged 62 to 92, from Manchester, England, had died with varying severities of neurodegenerative diseases. Such particles could conceivably contribute to diseases like Alzheimer's disease. Though a causal link has not been established, laboratory studies suggest that iron oxides like magnetite are a component of Senile plaques, protein plaques in the brain, linked to Alzheimer's disease. Increased iron levels, specifically magnetic iron, have been found in portions of the brain in Alzheimer's patients. Monitoring changes in iron concentrations may make it possible to detect the loss of neurons and the development of neurodegenerative diseases prior to the onset of symptoms due to the relationship between magnetite and ferritin. In tissue, magnetite and ferritin can produce small magnetic fields which will interact with magnetic resonance imaging (MRI) creating contrast. Huntington patients have not shown increased magnetite levels; however, high levels have been found in study mice.


Applications

Due to its high iron content, magnetite has long been a major
iron ore Iron ores are rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the way in which it is formed. Rock ...
. It is reduced in blast furnaces to pig iron or sponge iron for conversion to steel.


Magnetic recording

Audio recording using magnetic acetate tape was developed in the 1930s. The German magnetophon utilized magnetite powder as the recording medium. Following World War II, 3M Company continued work on the German design. In 1946, the 3M researchers found they could improve the magnetite-based tape, which utilized powders of cubic crystals, by replacing the magnetite with needle-shaped particles of Iron(III) oxide#Gamma phase, gamma ferric oxide (γ-Fe2O3).


Catalysis

Approximately 2–3% of the world's energy budget is allocated to the Haber Process for nitrogen fixation, which relies on magnetite-derived catalysts. The industrial catalyst is obtained from finely ground iron powder, which is usually obtained by reduction of high-purity magnetite. The pulverized iron metal is burnt (oxidized) to give magnetite or wüstite of a defined particle size. The magnetite (or wüstite) particles are then partially reduced, removing some of the
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
in the process. The resulting catalyst particles consist of a core of magnetite, encased in a shell of wüstite, which in turn is surrounded by an outer shell of iron metal. The catalyst maintains most of its bulk volume during the reduction, resulting in a highly porous high-surface-area material, which enhances its effectiveness as a catalyst.


Magnetite nanoparticles

Magnetite micro- and nanoparticles are used in a variety of applications, from biomedical to environmental. One use is in water purification: in high gradient magnetic separation, magnetite nanoparticles introduced into contaminated water will bind to the suspended particles (solids, bacteria, or plankton, for example) and settle to the bottom of the fluid, allowing the contaminants to be removed and the magnetite particles to be recycled and reused. This method works with radioactive and carcinogenic particles as well, making it an important cleanup tool in the case of heavy metals introduced into water systems. Another application of magnetic nanoparticles is in the creation of ferrofluids. These are used in several ways, in addition to being fun to play with. Ferrofluids can be used for targeted drug delivery in the human body. The magnetization of the particles bound with drug molecules allows “magnetic dragging” of the solution to the desired area of the body. This would allow the treatment of only a small area of the body, rather than the body as a whole, and could be highly useful in cancer treatment, among other things. Ferrofluids are also used in magnetic resonance imaging (MRI) technology.


Coal mining industry

For the Coal preparation plant, separation of coal from waste, dense medium baths were used. This technique employed the difference in densities between coal (1.3–1.4 tonnes per m³) and shales (2.2–2.4 tonnes per m³). In a medium with intermediate density (water with magnetite), stones sank and coal floated.


Magnetene

Magnetene is a 2 dimensional flat sheet of magnetite noted for its ultra-low-friction behavior.


Gallery of magnetite mineral specimens

File:Magnetite-278427.jpg, Octahedral crystals of magnetite up to 1.8 cm across, on cream colored feldspar crystals, locality: Cerro Huañaquino, Potosí Department, Bolivia File:Magnetite-170591.jpg, Magnetite crystals with epitaxial elevations on their faces File:Chalcopyrite-Magnetite-cktsr-10c.jpg, Magnetite in contrasting chalcopyrite matrix File:Magnetite-rw16b.jpg, Magnetite with a rare cubic habit from St. Lawrence County, New York


See also

* Bluing (steel), a process in which steel is partially protected against rust by a layer of magnetite * Buena Vista Iron Ore District * Corrosion product * Ferrite (magnet), Ferrite * Greigite * Magnesia (mineral), Magnesia (in natural mixtures with magnetite) * Mill scale * Magnes the shepherd * Rainbow lattice sunstone


References


Further reading

* *


External links


Mineral galleriesMagnetite mining in New Zealand
Accessed 25-Mar-09 {{Authority control Iron(II,III) minerals Spinel group Spinel gemstones Ferromagnetic materials Iron oxide pigments Cubic minerals Iron ores Magnetic minerals Ferrites