Magnetite

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Magnetite

Magnetite is not to be confused with Magnesite
Magnesite

Magnesite is magnesium carbonate, magnesiumcarbonoxygen3. Iron substitutes for magnesium with a complete solution series with siderite, FeCO3....
or Maghemite
Maghemite

Maghemite is a member of the family of iron oxides. It has the same structure as magnetite, that is, it is spinel Ferrite and is also ferrimagnetic....
.

Magnetite is a ferrimagnetic

Ferrimagnetism

In physics, a ferrimagnetic material is one in which the magnetic moment of the atoms on different sublattices are opposed, as in antiferromagnetism; however, in ferrimagnetic materials, the opposing moments are unequal and a spontaneous magnetization remains....
mineral

Mineral

A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
with chemical formula Fe
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
₃O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
₄, one of several iron oxide

Iron oxide

Iron oxides are chemical compounds composed of iron and oxygen. Altogether, there are sixteen known iron oxides and oxyhydroxides....
s and a member of the spinel

Spinel

The spinels are any of a class of minerals of general formulation A2+B23+oxygen42- which crystallise in the cubic crystal system crystal system, with the oxide anions arranged in a cubic close-packing Bravais lattice and the cations A and B occupying some or all of the octahedral molecul...
group. The chemical IUPAC name is iron(II,III) oxide
Iron(II,III) oxide

Iron oxide is the chemical compound with formula Fe3O4. It is one of a number of iron oxides. It is found in nature as the mineral magnetite....
and the common chemical name ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe₂O₃, which is one part wüstite

Wüstite

W?stite is a mineral form of iron oxide found with meteorites and native iron. It has a gray color with a greenish tint in reflected light. W?stite crystallizes in the Cubic crystal system in opaque to translucent metallic grains....
(FeO) and one part hematite

Hematite

Hematite, Spelling differences#Simplification of ae .28.C3.A6.29 and oe .28.C5.93.29 h?matite, is the mineral form of Iron oxide , one of several iron oxides....
(Fe₂O₃).

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Encyclopedia

Magnetite is a ferrimagnetic

Ferrimagnetism

Mineral

Iron oxide

Iron oxides are chemical compounds composed of iron and oxygen. Altogether, there are sixteen known iron oxides and oxyhydroxides....
s and a member of the spinel

Spinel

Wüstite

Hematite

Hematite, Spelling differences#Simplification of ae .28.C3.A6.29 and oe .28.C5.93.29 h?matite, is the mineral form of Iron oxide , one of several iron oxides....
(Fe₂O₃). This refers to the different oxidation states of the iron in one structure, not a solid solution

Solid solution

A solid solution is a solid-phase solution of one or more soluble in a solvent. Such a mixture is considered a solution rather than a Chemical compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single wiktionary:Homogeneous phase ....
.

The Curie temperature of magnetite is 858 K. Magnetite is the most magnetic of all the naturally occurring minerals on Earth

Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
, and these magnetic properties led to lodestone

Lodestone

Lodestone or loadstone refers to naturally occurring pieces of intensely magnetic magnetite that were used for magnetizing compasses.Iron, steel and ordinary magnetite are attracted to a magnetic field, including the Earth's magnetic field....
being used as an early form of magnetic compass

Compass

A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's magnetic poles....
. Magnetite typically carries the dominant magnetic signature in rocks, and so it has been a critical tool in paleomagnetism

Paleomagnetism

Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various magnetic minerals through time. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies substantially in both orientation and intensity through time....
, a science important in discovering and understanding plate tectonics

Plate tectonics

Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
and as historic data for magnetohydrodynamics

Magnetohydrodynamics

Magnetohydrodynamics is the academic discipline which studies the dynamics of electrical conduction fluids. Examples of such fluids include Plasma , liquid metals, and Brine....
and other scientific fields. The relationships between magnetite and other iron-rich oxide minerals such as ilmenite

Ilmenite

Ilmenite is a weakly Magnetism titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....
, hematite, and ulvospinel have been much studied, as the complicated reaction

Metamorphic reaction

A metamorphic reaction is a chemical reaction that takes place during the geological process of metamorphism in an amalgamate of minerals that helps determine the final stable state of the resulting metamorphic rock....
s between these minerals and oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
influence how and when magnetite preserves records of the Earth's magnetic field. Magnetite has been very important in understanding the conditions under which rocks form and evolve. Magnetite reacts with oxygen to produce hematite, and the mineral pair forms a buffer

Mineral redox buffer

In geology, a redox buffer is an assemblage of minerals or compounds that constrains oxygen fugacity as a function of temperature. Knowledge of the redox conditions at which a rock forms and evolves can be important for interpreting the rock history....
that can control oxygen fugacity

Fugacity

Fugacity is a measure of a chemical potential in the form of 'adjusted pressure.' It reflects the tendency of a substance to prefer one phase over another, and can be literally defined as ?the tendency to flee or escape?....
. Commonly igneous rock

Igneous rock

Igneous rock is one of the three main Rock types . Igneous rock is formed by magma being cooled and becoming solid . They may form with or without crystallization, either below the surface as Intrusion rocks or on the surface as extrusive rocks....
s contain grains of two solid solution

Solid solution

A solid solution is a solid-phase solution of one or more soluble in a solvent. Such a mixture is considered a solution rather than a Chemical compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single wiktionary:Homogeneous phase ....
s, one between magnetite and ulvospinel and the other between ilmenite and hematite. Compositions of the mineral pairs are used to calculate how oxidizing was the magma

Magma

Magma is molten Rock that is found beneath the surface of the Earth, and may also exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and gas bubbles....
(i.e., the oxygen

Oxygen

Fugacity

Mineral redox buffer

Fractional crystallization (geology)

Fractional crystallization is one of the most important geochemical and physical processes operating within the Earth's crust and Earth's mantle....
.

Small grains of magnetite occur in almost all igneous rocks and metamorphic rocks. Magnetite also occurs in many sedimentary rocks, including banded iron formation

Banded iron formation

Banded iron formations are a distinctive type of rock often found in primordial sedimentary rocks. The structures consist of repeated thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert....
s. In many igneous rocks, magnetite-rich and ilmenite-rich grains occur that precipitated together from magma

Magma

Peridotite

A peridotite is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic and ultrabasic, as the rock contains less than 45% silica....
s and dunite

Dunite

Dunite is an igneous rock, 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....
s by serpentinization

Serpentinite

Serpentinite is a Rock composed of one or more serpentine minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic rock transformation of ultramafic rock from the Earth's Mantle ....
.

Magnetite is a valuable source of iron ore

Iron ore

Iron ores are Rock and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, deep purple, to rusty red....
. It dissolves slowly in hydrochloric acid

Hydrochloric acid

Hydrochloric acid is the solution of hydrogen chloride in water. It is a highly corrosive, strong acid mineral acid and has major industrial uses....
.

Distribution of deposits

Magnetite is sometimes found in large quantities in beach sand. Such mineral sands or iron sand

Iron Sand

Iron sand may refer to:* Black sand - sand contain iron particles* List of minor Naruto characters#Third Kazekage - a character in Naruto...
s or black sand

Black sand

Black sand is sand that is black in colour. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands, found as part of a placer deposit....
s are found in various places such as California

California

California is a U.S. state on the West Coast of the United States of the United States, along the Pacific Ocean. It is bordered by Oregon to the north, Nevada to the east, Arizona to the southeast, and to the south the Mexico state of Baja California....
and the west coast of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous Islands of New Zealand, most notably Stewart Island/Rakiura and the Chatham Islands....
. The magnetite is carried to the beach via rivers from erosion and is concentrated via 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 also are found in Kiruna

Kiruna

Kiruna is the northernmost Stad in Sweden, situated in Lapland, Sweden province, with 18,154 inhabitants in 2005. It is the seat of Kiruna Municipality in Norrbotten County....
, Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic countries on the Scandinavian Peninsula in Northern Europe. Sweden has land borders with Norway to the west and Finland to the northeast, and it is connected to Denmark by the ?resund Bridge in the south....
, the Pilbara region in Western Australia

Western Australia

Western Australia is a States and territories of Australia occupying the entire western third of the Australia . The nation's largest state and the second largest subnational entity in the world, it has 2.1 million inhabitants , 85% of whom live in the south-west corner of the state....
, and in the Adirondack

Adirondack Mountains

The Adirondack Mountains are a mountain range located in the northeastern part of New York, that runs through Clinton County, New York, Essex County, New York, Franklin County, New York, Fulton County, New York, Hamilton County, New York, Herkimer County, New York, Lewis County, New York, Saint Lawrence County, New York, Saratoga County, New...
region of New York

New York

The State of New York is a U.S. state in the Mid-Atlantic States and Northeastern United States regions of the United States and is the nation's List of U.S....
in the United States

United States

The United States of America is a Federal government constitutional republic comprising U.S. state and a federal district. The country is situated mostly in central North America, where its Contiguous United States and Washington, D.C., the Capital districts and territories, lie between the Pacific Ocean and Atlantic Oceans, Borders of the U...
. Deposits are also found in Norway

Norway

Norway , officially the Kingdom of Norway, is a constitutional monarchy in Northern Europe that occupies the western portion of the Scandinavian Peninsula....
, Germany

Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
, Italy

Italy

Italy , officially the Italian Republic , is a country located on the Italian Peninsula in Southern Europe and on the two largest islands in the Mediterranean Sea, Sicily and Sardinia....
, Switzerland

Switzerland

Switzerland is a landlocked Swiss Alps country of roughly 7.7 million people in Western Europe with an area of 41,285 km?. Switzerland is a federal republic consisting of 26 states called Cantons of Switzerland....
, South Africa

South Africa

The Republic of South Africa, also known by Official names of South Africa, is a country located at the southern tip of the continent of Africa....
, India

India

India, officially the Republic of India , is a country in South Asia. It is the List of countries and outlying territories by total area country by geographical area, the List of countries by population country, and the most populous liberal democracy in the world....
, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federalism constitutionalism republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of Mexico....
, and in Oregon

Oregon

Oregon is a U.S. state in the Pacific Northwest region of the United States. The area was inhabited by many indigenous tribes before the arrival of traders, explorers and settlers....
, New Jersey

New Jersey

New Jersey is a state in the Mid-Atlantic States and Northeastern United States regions of the United States. It is bordered on the north by New York, on the east by the Hudson River and the Atlantic Ocean, on the southwest by Delaware, and on the west by Pennsylvania....
, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania , often colloquially referred to as PA by natives and Northeasterners, is a U.S. state located in the Northeastern United States and Mid-Atlantic States regions of the United States....
, North Carolina

North Carolina

North Carolina is a U.S. state located on the Atlantic Seaboard in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north....
, Virginia

Virginia

The Commonwealth of Virginia is an United States U.S. state on the East Coast of the United States of the Southern United States. The state is known as the "Old Dominion" and sometimes as "Mother of Presidents", because it is the birthplace of Lists of United States Presidents by place of birth#By state....
, New Mexico

New Mexico

New Mexico is a U. S. State located in the Southwestern United States of the United States. Inhabited by Native Americans in the United States populations for many centuries, it has also has been part of the Spanish Empire viceroyalty of New Spain, part of Mexico, and a U.S....
, Utah

Utah

The State of Utah is a western United States U.S. state of the United States. It was the List of U.S. states by date of statehood admitted to the United States on January 4, 1896....
, and Colorado

Colorado

The State of Colorado is a U.S. state located in the Mountain States of the United States of America. Colorado may also be considered to be a part of the Western United States and Southwestern United States regions of the United States....
in the United States

United States

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
. 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.

Biological occurrences

Crystals of magnetite have been found in some bacteria (e.g., Magnetospirillum magnetotacticum) and in the brains of bees, of termites, fish and of some birds (e.g., the pigeon). These crystals are thought to be involved in magnetoreception, the ability to sense the polarity or the inclination

Inclination

Inclination in general is the angle between a reference plane and another plane or Axis_of_rotation of direction. The axial tilt is expressed as the angle made by the planet's axis and a line drawn through the planet's center perpendicular to the orbital plane....
of the Earth's magnetic field

Magnetic field

A magnetism field is a vector field which can exert a magnetic force on moving electric charges and on magnetic dipoles . When placed in a magnetic field, magnetic dipoles tend to align their axes parallel to the magnetic field....
, and to be involved in navigation

Navigation

Navigation is the process of reading, and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks....
. Also, chitons have teeth made of magnetite on their radula

Radula

The radula is an anatomical structure found in mollusks and used for feeding. It is a minutely toothed, chitinous ribbon. It is typically used for scraping or cutting food before the food enters the esophagus....
making them unique among animals. This means they have an exceptionally abrasive tongue with which to scrape food from rocks.

The study of biomagnetism

Biomagnetism

Biomagnetism is the phenomenon of magnetic fields produced by the human body, and other living entities. It is to be distinguished from magnetic fields applied to the body, properly called magnetobiology....
began with the discoveries of Caltech paleoecologist

Paleoecology

Paleoecology uses data from fossils and subfossils to reconstruct the ecosystems of the past. It includes the study of fossil organisms and their bromalites and other trace fossils in terms of their Biological life cycle, their living interactions, their natural environment, their manner of death and burial....
Heinz Lowenstam

Heinz A. Lowenstam

Heinz Adolf Lowenstam was German-born, Jewish-American Paleoecology celebrated for his discoveries in biomineralization: that living organisms manufacture substances such as the iron-containing mineral magnetite within their bodies....
in the 1960s.

Preparation as a ferrofluid

Magnetite can be prepared in the laboratory as a ferrofluid

Ferrofluid

A ferrofluid is a liquid which becomes strongly polarised in the presence of a magnetic field.Ferrofluids are colloidal mixtures composed of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a Wiktionary:carrier fluid, usually an organic solvent or water....
in the Massart method by mixing iron(II) chloride

Iron(II) chloride

Iron chloride, also known as ferrous chloride, is the chemical compound of formula FeCl2. It has a high melting point, paramagnetic solid, usually obtained as an off-white solid....
and iron(III) chloride

Iron(III) chloride

Iron chloride, Generic name called ferric chloride, is an industrial scale commodity chemical compound, with the formula IronChlorine3....
in the presence of sodium hydroxide

Sodium hydroxide

Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
.

Magnetite also can be prepared by chemical co-precipitation, which consist in a mixture of a solution 0.1 M of FeCl₃.6H₂O and FeCl₂.4H₂O with mechanic agitation of about 2000 rpm. The molar ratio of FeCl₃:FeCl₂ can be 2:1; heating this solution at 70 °C, and immediately the rpm is elevated to 7500 rpm and adding quickly a solution of NH₄OH (10% in v.), immediately a dark precipitate will be formed, which consist of nanoparticles of magnetite.

Application as a sorbent

Magnetite powder efficiently removes As(III) and As(V) from water, and the efficiency of the removal increases ~200 times when the magnetite particle size decreases from 300 to 12 nm . Arsenic(As)-contaminated drinking water is a major problem around the world, which can be solved using magnetite as a sorbent.

Magnetite

Distribution of deposits

Biological occurrences

Preparation as a ferrofluid

Application as a sorbent

See also

Mineralogy related

Biology related

Mining related links