Goethite

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Goethite

Goethite, named after the German

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....
polymath

Polymath

A polymath is a person whose knowledge is not restricted to one subject area. In less formal terms, a polymath may simply refer to someone who is very knowledgeable....
Johann Wolfgang von Goethe

Johann Wolfgang von Goethe

was a Germans writer and according to George Eliot, "Germany's greatest man of letters? and the last true polymath to walk the earth." Goethe's works span the fields of poetry, drama, literature, theology, philosophy, humanism and science....
, is an iron bearing oxide mineral found in soil and other low-temperature environments. Goethite has been well known since prehistoric times for its use as a pigment

Pigment

A pigment is a material that changes the color of light it Reflection as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light....
. Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux

Lascaux

Lascaux is the setting of a complex of caves in southwestern France famous for its prehistory cave paintings. The original caves are located near the village of Montignac, Dordogne, in the Dordogne d?partement in France....
in France

France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
. It was first described in 1806 for occurrences in the Mesabi

Mesabi Range

The Mesabi Iron Range is a vast deposit of iron ore and the largest of four major iron ranges in the region collectively known as the Iron Range of Minnesota....
iron ore district of Minnesota

Minnesota

Minnesota is a U.S. state in the Midwestern United States of the United States. The twelfth largest state by area in the U.S., it is the twenty-first most populous, with just over five million residents....
. Recently, nanoparticulate authigenic

Authigenic

An authigenic mineral or sedimentary rock deposit is one that was generated where it is found or observed. Can be used to characterize metamorphic minerals formed in situ during metamorphism, or to characterize sedimentary minerals formed during sedimentation instead of being transported from elsewhere by water or wind....
goethite was shown to be the most common diagenetic

Diagenesis

In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration and metamorphism....
iron oxyhydroxide in both marine and lake sediments.
Composition
It is an iron oxyhydroxide

Iron(III) oxide-hydroxide

A number of species are dubbed iron oxide-hydroxide. These chemicals are oxide-hydroxides of iron, and may occur in anhydrous or hydrated forms....
.

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Encyclopedia

Goethite, named after the German

Germany

Polymath

A polymath is a person whose knowledge is not restricted to one subject area. In less formal terms, a polymath may simply refer to someone who is very knowledgeable....
Johann Wolfgang von Goethe

Johann Wolfgang von Goethe

Pigment

Lascaux

France

Mesabi Range

The Mesabi Iron Range is a vast deposit of iron ore and the largest of four major iron ranges in the region collectively known as the Iron Range of Minnesota....
iron ore district of Minnesota

Minnesota

Authigenic

Diagenesis

Composition

It is an iron oxyhydroxide

Iron(III) oxide-hydroxide

A number of species are dubbed iron oxide-hydroxide. These chemicals are oxide-hydroxides of iron, and may occur in anhydrous or hydrated forms....
. Goethite's hardness ranges from 5.0 to 5.5 on the Mohs Scale

Mohs scale of mineral hardness

Not to be confused with Siemens_#Mho, a unit of electric conductance.The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material....
, and its specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
varies from 3.3 to 4.3. The mineral forms prismatic needle-like crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions....
s, but is more typically massive.

Feroxyhyte

Feroxyhyte

Feroxyhyte is an iron oxide-hydroxide, d-FeO. It occurs in manganese-iron Manganese nodule on the Pacific Ocean floor. Forms under high pressure conditions and reverts to goethite on exposure to surface conditions....
and Lepidocrocite

Lepidocrocite

Lepidocrocite , also called esmeraldite or hydrohematite, is an iron oxide-hydroxide mineral. Lepidocrocite has an orthorhombic crystal structure, a Mohs scale of mineral hardness of 5, specific gravity of 4, a submetallic Lustre and a yellow-brown streak....
are both polymorphs of the iron oxyhydroxide FeO(OH). Although they have the same chemical formula as goethite they each have different crystalline structures making them distinct minerals.

Usage

Its main modern use is as an 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....
, being referred to as brown iron ore. It does have some use as a clay earth pigment

Clay earth pigment

Clay earth pigments are naturally occurring minerals, principally iron oxides, that have been used since prehistoric times as pigments. The primary types are...
. Iron rich lateritic

Laterite

Laterite is a surface formation in hot and wet tropical areas which is enriched in iron and aluminium and develops by intensive and long lasting weathering of the underlying parent rock....
soils developed over serpentinite

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 ....
rocks in tropical climates are mined for their iron content as well as other metals.

Formation

Goethite often forms through the weathering

Weathering

Weathering is the decomposition of earth Rock , soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity....
of other iron-rich minerals, and thus is a common component of soil

Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
s. It may also be precipitated by groundwater

Groundwater

Groundwater is water located beneath the ground surface in soil porosity spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water....
or in other sedimentary conditions, or form as a primary mineral in hydrothermal deposits.

Prevalence

Goethite is found all over the planet, usually in the form of concretion

Concretion

A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur....
s, stalactitic

Stalactite

A stalactite is a type of speleothem that hangs from the ceiling or wall of limestone caves. It is sometimes referred to as dripstone....
formations, oolite

Oolite

Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word ?oion for egg ....
s (a form consisting of tiny round grains cemented together), reniform (kidney shapes) or botryoidal (globular, like bunches of grapes) accumulations. It is frequently encountered in the swampy areas at the head of spring waters ('bog iron

Bog iron

Bog iron refers to impure iron deposits that develop in bogs or swamps by the chemical or biochemical oxidation of iron carried in the solutions....
'), on cave floors, and on the bottom of lakes and small creeks. The boxworks or gossan

Gossan

Gossan is intensely oxidized, weathering or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein. In the classic gossan or iron cap all that remains is iron oxides and quartz often in the form of boxworks, quartz lined cavities retaining the shape of the dissolved ore minerals....
resulting from the 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

Australia

Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
, Cuba

Cuba

The Republic of Cuba is a country in the Caribbean. It consists of the island of Cuba , the island of Isla de la Juventud, and several adjacent small islands....
, and Michigan

Michigan

Michigan is a Midwestern United States U.S. state of the United States of America. It was named after Lake Michigan, whose name is a French adaptation of the Anishinaabe language term mishigama, meaning "large water" or "large lake"....
, Minnesota

Minnesota

Missouri

Missouri is a U.S. state in the Midwestern United States of the United States bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska....
, 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....
, Alabama

Alabama

Alabama is a state located in the Southern United States of the United States of America. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west....
, Georgia

Georgia (U.S. state)

Georgia is a U.S. state in the United States and was one of the original Thirteen Colonies that revolted against United Kingdom rule in the American Revolution....
, 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....
, and Tennessee

Tennessee

Tennessee is a U.S. state located in the Southern United States United States. In 1796, it became the sixteenth state to join the United States....
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 significant in location, if not in abundance, have been found in Gusev by NASA's Spirit rover, providing strong evidence for the presence of liquid water on the planet Mars in an earlier stage of its development.

Goethite

Composition

Usage

Formation

Prevalence

See also