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Goethite (, ) is a mineral of the
diaspore Diaspore , also known as diasporite, empholite, kayserite, or tanatarite, is an aluminium oxide hydroxide Aluminium hydroxide oxide or aluminium oxyhydroxide, AlO(OH) is found as one of two well defined crystalline phases, which are also known ...

diaspore
group, consisting of
iron(III) oxide-hydroxide Iron(III) oxide-hydroxide or ferric oxyhydroxideA. L. Mackay (1960): "β-Ferric Oxyhydroxide". ''Mineralogical Magazine'' (''Journal of the Mineralogical Society''), volume 32, issue 250, pages 545-557. is the chemical compound of iron Iron ...
, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient times for its use as a
pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compound , CH4; is among the simplest organic compou ...
(brown
ochre Ochre ( ; from grc, ὤχρα, from , , pale), or ocher in American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the ...
). Evidence has been found of its use in paint pigment samples taken from the
caves of Lascaux
caves of Lascaux
in
France France (), officially the French Republic (french: link=no, République française), is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses ...

France
. It was first described in 1806 based on samples found in the Hollertszug Mine in
Herdorf Herdorf () is a town in the Altenkirchen (district), district of Altenkirchen, in Rhineland-Palatinate, Germany. It is situated on the river Heller River, Heller, approx. 20 km south-west of Siegen. Twin towns — sister cities Herdorf is to ...
,
Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin Berlin (; ) is the Capital city, capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3,769,495 inh ...

Germany
. The mineral was named after the
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

German
polymath A polymath ( el, πολυμαθής, , "having learned much"; la, homo universalis, "universal human") is an individual whose knowledge spans a substantial number of subjects, known to draw on complex bodies of knowledge to solve specific pro ...

polymath
and poet
Johann Wolfgang von Goethe Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of G ...

Johann Wolfgang von Goethe
(1749–1832).


Composition

Goethite is an iron oxyhydroxide containing
ferric In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in th ...

ferric
iron. It is the main component of
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous ferric oxides, hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxi ...

rust
and
bog iron Bog iron is a form of impure iron deposit that develops in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)). Iron-bearin ...

bog iron
ore. Goethite's hardness ranges from 5.0 to 5.5 on the
Mohs Scale The Mohs scale of mineral hardness () is a qualitative ordinal scale Ordinal data is a categorical, statistical data type where the variables have natural, ordered categories and the distances between the categories are not known. These data e ...
, and its
specific gravity Relative density, or specific gravity, is the ratio In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemon ...
varies from 3.3 to 4.3. The mineral forms prismatic needle-like
crystal A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformatio ...

crystal
s ("needle iron ore") but is more typically massive.
Feroxyhyte Feroxyhyte is an oxide/hydroxide of iron, δ-Fe3+O(OH). Feroxyhyte crystallize Crystallization or crystallisation is the process by which a solid forms, where the atoms or molecules are highly organized into a structure known as a crystal ...
and
lepidocrocite Lepidocrocite (γ-FeO(OH)), also called esmeraldite or hydrohematite, is an iron oxide-hydroxide mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chem ...
are both polymorphs of the iron oxyhydroxide FeO(OH) which are stable at the pressure and temperature conditions of the Earth's surface. Although they have the same chemical formula as goethite, their different crystalline structures make them distinct minerals. Additionally, goethite has several high-pressure and high-temperature polymorphs, which may be relevant to the conditions of the Earth's interior. These include ε-FeOOH, which has an orthorhombic crystal structure, a cubic
pyrite The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. ...

pyrite
-type polymorph with or without losing hydrogen and an ultradense hexagonal structure.


Formation

Goethite often forms through the
weathering Weathering is the deterioration of Rock (geology), rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little o ...
of other iron-rich minerals, and thus is a common component of
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
s, concentrated in
laterite Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by in ...
soils.
authigenic Authigenesis is the process whereby a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs ...
goethite is a common
diagenetic Diagenesis () is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a r ...
iron oxyhydroxide in both marine and lake sediments. The formation of goethite is marked by the oxidation state change of Fe2+ (ferrous) to Fe3+ (ferric), which allows for goethite to exist at surface conditions. Because of this oxidation state change, goethite is commonly seen as a
pseudomorph In mineralogy Mineralogy is a subject of 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 o ...

pseudomorph
. As iron-bearing minerals are brought to the zone of oxidation within the soil, the iron turns from iron(II) to iron(III), while the original shape of the parent mineral is retained. Examples of common goethite pseudomorphs are: goethites after pyrite, goethite, siderite, and marcasite, though any iron(II)-bearing mineral could become a goethite pseudomorph if proper conditions are met. It may also be precipitated by
groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

groundwater
or in other sedimentary conditions, or form as a primary mineral in
hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí ...
deposits. Goethite has also been found to be produced by the excretion processes of certain bacteria types.


Distribution

Goethite is found all over the planet, usually in the form of
concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition ...

concretion
s, formations,
oolite Oolite or oölite (''egg stone'') is a sedimentary rock Sedimentary rocks are types of rock Rock most often refers to: * Rock (geology) A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It ...

oolite
s (a form consisting of tiny round grains cemented together), reniform (kidney shapes) or botryoidal (globular, like bunches of grapes) accumulations. It is also a very common pseudomorph. It is frequently encountered in the swampy areas at the head of spring waters ('
bog iron Bog iron is a form of impure iron deposit that develops in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)). Iron-bearin ...

bog iron
'), on cave floors, and on the bottom of lakes and small creeks. The ''boxworks'' or
gossan Gossan (eiserner hut or eisenhut) is intensely oxidized (mild reducing agent) are added to powdered potassium permanganate (strong oxidizing agent), a violent redox reaction accompanied by self-ignition starts. Redox (reduction–oxidation, ...
resulting from the
oxidation Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...

oxidation
of sulfide ore deposits is formed of goethite along with other iron oxides and quartz. Significant deposits of goethite are found in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest of England and the Celtic Sea to the southwest. E ...

England
,
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
,
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is a country comprising the island of Cuba, as well as Isla de la Juventud Isla de la Juventud (; en, Isle of Youth) is the second-largest Cuban islan ...

Cuba
, and
Michigan Michigan () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

Michigan
,
Minnesota Minnesota () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

Minnesota
,
Missouri Missouri is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper in ...

Missouri
,
Colorado Colorado (, other variants) is a state in the Mountain West The Mountain West Conference (MW) is one of the collegiate athletic conferences affiliated with the National Collegiate Athletic Association The National Collegiate Athletic ...

Colorado
,
Alabama (We dare defend our rights) , anthem = "Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat ...

Alabama
,
Georgia Georgia usually refers to: * Georgia (country) Georgia (, ; ) is a country located at the intersection of Eastern Europe and Western Asia. It is a part of the Caucasus region, bounded to the west by the Black Sea, to the north and east by ...
,
Virginia Virginia (), officially the Commonwealth of Virginia, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), '' ...

Virginia
, and
Tennessee Tennessee (, ), officially the State of Tennessee, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The S ...

Tennessee
, and Florida caves in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
. Deposits significant in location, if not in abundance, have been found in the
Martian A Martian is an inhabitant of the planet Mars or a Colonization of Mars, human colonist on Mars. Although the search for evidence of life on Mars continues, many science fiction writers have imagined what extraterrestrial life on Mars might be l ...

Martian
crater Gusev by NASA's ''
Spirit Spirit may refer to: *Spirit (animating force) In folk belief, spirit is the vitalism , vital principle or animating force within all life , living things. As recently as 1628 and 1633 respectively, both William Harvey and René Descartes st ...
'' rover, providing strong evidence for the presence of liquid water on the planet in an earlier stage of its evolution. Limpets' teeth are composed of about 80% goethite fibres of only tens of nanometers in diameter, small enough to be flaw-insensitive, which accounts for their extreme
tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle tensi ...
of 3.5–6.0 GPa and
elastic modulus An elastic modulus (also known as modulus of elasticity) is a quantity that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. The elastic modulus of an object is def ...
of 120±30 GPa.


Usage

Its main modern use is as an
iron ore Iron ores are rocks 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 i ...
, being referred to as ''brown iron ore''. It does have some use as a
clay earth pigment Earth pigments are naturally occurring mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occu ...
. Iron-rich
lateritic Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by in ...
soils that have developed over
serpentinite Serpentinite is a rock Rock most often refers to: * Rock (geology) 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, chemic ...

serpentinite
rocks in tropical climates are mined for their iron content, as well as other metals. Fine goethite specimens are rare and therefore are valued collectibles. Banded or iridescent varieties are cut and polished into
cabochons A cabochon (, from Middle French Middle French (french: moyen français) is a historical division of the French language French ( or ) is a Romance language The Romance languages, less commonly Latin or Neo-Latin languages, are th ...

cabochons
for jewelry making. Perhaps the oldest known use of goethite comes from the ancient kingdom of
Phrygia In classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history History (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related ...
. In a royal tomb a body was found believed to be King
Gordias Gordias ( grc, Γορδίας, ''Gordías''; also Γόρδιος, ''Górdios'', "Gordius") was the name of at least two members of the royal house of Phrygia. The best-known Gordias was reputedly the founder of the Phrygian capital city Gordium, t ...
, father of the legendary King
Midas Midas (; grc-gre, Μίδας) is the name of one of at least three members of the royal house of Phrygia In classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cul ...

Midas
. The burial shroud had been colored with a dye containing goethite, which in its original unfaded state would have made the shroud look like it was woven from gold. Historians speculate that the legend of King Midas' golden touch might have originated from Phrygian royalty wearing clothes made from such golden-colored textiles.Archived a
Ghostarchive
and th
Wayback Machine


Gallery

File:Goethite-242608.jpg,
Iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States Engl ...
goethite, Filón Sur Mine, Tharsis, Huelva, Spain File:Goethite3.jpg, Goethite from
Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by Gross Domestic Product, gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo ...

Minas Gerais
, Brazil File:Goethite-Calcite-Feldspar-Group-215498.jpg, A sharp, disc-shaped calcite has here been completely replaced by goethite, which preserved the original form perfectly File:PyOx.JPG, Goethite coating/replacing rusted
pyrite The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. ...

pyrite
cubes File:Goethite-162473.jpg, Finely crystallized specimen of goethite from Lake George, Park County,
Colorado Colorado (, other variants) is a state in the Mountain West The Mountain West Conference (MW) is one of the collegiate athletic conferences affiliated with the National Collegiate Athletic Association The National Collegiate Athletic ...

Colorado
, USA File:Harvard Museum of Natural History. Goethite. Negaunee, Marquette Co., MI (DerHexer) 2012-07-20.jpg, Goethite from Negaunee, Marquette County, Michigan


See also

*
Ochre Ochre ( ; from grc, ὤχρα, from , , pale), or ocher in American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the ...
*
List of minerals This is a list of minerals for which there are articles on Wikipedia. Mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specif ...


References


External links

* {{Authority control Iron(III) minerals Iron oxide pigments Hydroxide minerals Johann Wolfgang von Goethe Orthorhombic minerals Minerals in space group 62 Iron ores Magnetic minerals