Jarosite
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Jarosite is a basic
hydrous In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was underst ...
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...
of
potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
and ferric
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
(Fe-III) with a chemical formula of KFe3(SO4)2(OH)6. This
sulfate mineral The sulfate minerals are a class of minerals that include the sulfate ion () within their structure. The sulfate minerals occur commonly in primary evaporite depositional environments, as gangue minerals in hydrothermal veins and as secondary mine ...
is formed in
ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
deposits by the
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
of iron
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
s. Jarosite is often produced as a byproduct during the purification and refining of
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
and is also commonly associated with
acid mine drainage Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines. Acid rock drainage occurs naturally within some environments as part of the rock weathering ...
and
acid sulfate soil Acid sulfate soils are naturally occurring soils, sediments or organic substrates (e.g. peat) that are formed under waterlogged conditions. These soils contain iron sulfide minerals (predominantly as the mineral pyrite) and/or their oxidation produ ...
environments.


Physical properties

Jarosite has a
trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crysta ...
crystal structure and is brittle, with basal cleavage, a
hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
of 2.5-3.5, and a
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...
of 3.15-3.26. It is translucent to opaque with a vitreous to dull luster, and is colored dark yellow to yellowish-brown. It can sometimes be confused with
limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydroxid ...
or
goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...
with which it commonly occurs in the
gossan Gossan (eiserner hut or eisenhut) is intensely oxidized, weathered 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 ...
(oxidized cap over an ore body). Jarosite is an iron analogue of the potassium aluminium sulfate, alunite.


Solid solution series

The alunite supergroup includes the alunite, jarosite,
beudantite 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. Beudantite is in a subgroup of the alunite group. It is the arsenate an ...
,
crandallite Crandallite is a calcium aluminium basic phosphate mineral. It has ideal formula . Crandallite was named after Milan L. Crandall, Jr, who worked for Knight Syndicate. This mineral is found in laterite and in alteration products of phosphate rich ...
and
florencite Florencite-(Sm) is a very rare mineral of the plumbogummite group (alunite supergroup) with simplified formula SmAl3(PO4)2(OH)6. Samarium in florencite-(Sm) is substituted by other rare earth elements, mostly neodymium. It does not form separate c ...
subgroups. The alunite supergroup minerals are isostructural with each other and substitution between them occurs, resulting in several
solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word ...
series. The alunite supergroup has the general formula AB3(TO4)2(OH)6. In the alunite subgroup B is Al, and in the jarosite subgroup B is Fe3+. The beudantite subgroup has the general formula AB3(XO4)(SO4)(OH)6, the crandallite subgroup AB3(TO4)2(OH)5•H2O and the florencite subgroup AB3(TO4)2(OH)5 or 6. In the jarosite-alunite series Al may substitute for Fe and a complete solid solution series between jarosite and alunite, KAl3(SO4)2(OH)6, probably exists, but intermediate members are rare. The material from
Kopec KEPCO E&C (full name: KEPCO Engineering & Construction Company, INC., formerly: KOPEC) is a power plant design and engineering company in South Korea. It was established in 1975 as a public enterprise. KEPCO E&C engages in designing, engineering, ...
,
Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
, has about equal Fe and Al, but the amount of Al in jarosite is usually small. When jarosite forms from
pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
in sedimentary clays, the main sources of K+ are
illite Illite is a group of closely related non-expanding clay minerals. Illite is a secondary mineral precipitate, and an example of a phyllosilicate, or layered alumino-silicate. Its structure is a 2:1 sandwich of silica tetrahedron (T) – alumina ...
, a non-swelling clay, or
K-feldspar Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles t ...
. In other geological settings
mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
's alteration can also be a source of potassium. In the jarosite-natrojarosite series Na substitutes for K to at least Na/K = 1:2.4 but the pure sodium end member NaFe3(SO4)2(OH)6 is not known in nature. Minerals with Na > K are known as natrojarosite. End member formation (jarosite and natrojarosite) is favoured by a low temperature environment, less than 100 °C, and is illustrated by the oscillatory zoning of jarosite and natrojarosite found in samples from the Apex Mine, Arizona, and
Gold Hill, Utah Gold Hill is an unincorporated community in far western Tooele County, Utah, located near the Nevada state line. History The town, located near the Deep Creek Mountains, was the center of a mining district that was active in the late nineteenth ...
. This indicates that there is a wide
miscibility gap A miscibility gap is a region in a phase diagram for a mixture of components where the mixture exists as two or more phases – any region of composition of mixtures where the constituents are not completely miscible. The IUPAC Gold Book defines ...
between the two end members,American Mineralogist (2007) 92:444-447 and it is doubtful whether a complete series exists between jarosite and natrojarosite. In hydroniumjarositeAmerican Mineralogist (2007) 92:1464-1473 the
hydronium In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation , the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is d ...
ion H3O+ can also substitute for K+, with increased hydronium ion content causing a marked decrease in the lattice parameter ''c'', although there is little change in ''a''.American Mineralogist (1965) 50:1595-1607 Hydroniumjarosite will only form from alkali-deficient solutions, as alkali-rich jarosite forms preferentially. Divalent cations may also substitute for the monovalent cation K+ in the A site.American Mineralogist (1987) 72:178-187 Charge balance may be achieved in three ways. :Firstly by replacing two monovalent cations by one divalent cation, and leaving an A site vacancy, as in plumbogummite, Pb2+Al3(PO4)2(OH)5.H2O, which is a member of the crandallite subgroup. :Secondly by incorporating divalent ions in the B sites, as in
osarizawaite Osarizawaite is a greenish yellow sulfate mineral with the chemical formula: Pb Cu Al2( S O4)2(O H)6. It has rhombohedral In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a three-dimensional figu ...
, Pb2+Cu2+Al2(SO4)2(OH)6, alunite subgroup, and beaverite, Pb2+Cu2+(Fe3+,Al)2(SO4)2(OH)6, jarosite subgroup. :Thirdly by replacing divalent anions with trivalent anions, as in
beudantite 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. Beudantite is in a subgroup of the alunite group. It is the arsenate an ...
, PbFe3+3(AsO4)3−(SO4)(OH)6, beudantite subgroup.


History

Jarosite was first described in 1852 by
August Breithaupt Johann Friedrich August Breithaupt (May 16, 1791 – September 22, 1873) was a German mineralogist and professor at Freiberg Mining Academy in Freiberg, Saxony. Biography He was born in Probstzella. He received his doctorate at the Universities ...
in the Barranco del Jaroso in the Sierra Almagrera (near Los Lobos, Cuevas del Almanzora,
Almería Almería (, , ) is a city and municipality of Spain, located in Andalusia. It is the capital of the province of the same name. It lies on southeastern Iberia on the Mediterranean Sea. Caliph Abd al-Rahman III founded the city in 955. The city gr ...
,
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
). The name jarosite is also directly derived from Jara, the Spanish name of a yellow flower that belongs to the genus ''
Cistus ''Cistus'' (from the Greek ''kistos'') is a genus of flowering plants in the rockrose family Cistaceae, containing about 20 species (Ellul ''et al.'' 2002). They are perennial shrubs found on dry or rocky soils throughout the Mediterranean region ...
'' and grows in this sierra. The mineral and the flower have the same color. Mysterious spheres of clay 1.5 to 5 inches in diameter and covered with jarosite have been found beneath the
Temple of the Feathered Serpent The Temple of the Feathered Serpent is the third largest pyramid at Teotihuacan, a Pre-Columbian Mexico, pre-Columbian site in central Mexico (the term ''Teotihuacan'', or ''Teotihuacano'', is also used for the whole civilization and cultural com ...
an ancient six level stepped pyramid 30 miles from Mexico City.


Mars exploration

Ferric sulfate and jarosite have been detected by three martian rovers: ''
Spirit Spirit or spirits may refer to: Liquor and other volatile liquids * Spirits, a.k.a. liquor, distilled alcoholic drinks * Spirit or tincture, an extract of plant or animal material dissolved in ethanol * Volatile (especially flammable) liquids, ...
'', ''
Opportunity Opportunity may refer to: Places * Opportunity, Montana, an unincorporated community, United States * Opportunity, Nebraska, an unincorporated community, United States * Opportunity, Washington, a former census-designated place, United States * 3 ...
'' and ''
Curiosity Curiosity (from Latin '' cūriōsitās'', from ''cūriōsus'' "careful, diligent, curious", akin to ''cura'' "care") is a quality related to inquisitive thinking such as exploration, investigation, and learning, evident by observation in humans ...
''. These substances are indicative of strongly oxidizing conditions prevailing at the surface of
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
. In May 2009, the ''Spirit'' rover became stuck when it drove over a patch of soft ferric sulfate that had been hidden under a veneer of normal-looking soil. Because iron sulfate has very little cohesion, the rover's wheels could not gain sufficient traction to pull the body of the rover out of the iron sulfate patch. Multiple techniques were attempted to extricate the rover, but the wheels eventually sank so deeply into the iron sulfate that the body of the rover came to rest on the Martian surface, preventing the wheels from exerting any force on the material below them. As the JPL team failed to recover the mobility of ''Spirit'', it signified the end of the journey for the rover.


Antarctica deep borehole

On Earth, jarosite is mainly associated with the ultimate stage of pyrite oxidation in clay environment and can also be found in
mine tailings In mining, tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different to overburden, which is the waste rock or other material that overlie ...
waste where acidic conditions prevail. Against all expectations, jarosite has also been fortuitously discovered in minute quantities in the form of small dust particules in ice cores recovered from a deep borehole in
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. This surprising discovery was made by geologists who were searching for specific minerals capable to indicate ice age cycles within the layers of a 1620 meters-long ice core. Geologists speculate that jarosite dust could also have accumulated within ice on glaciers on Mars. However, this hypothesis is a matter of controverses, because on Mars jarosite deposits can be very thick (up to 10 meters); but Mars is also a very dusty planet and in the absence of
plate tectonic Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
on Mars glacial dust deposits might have accumulated during long periods of time.


Use in materials science

Jarosite is also a more generic term denoting an extensive family of compounds of the form AM3(OH)6(SO4)2, where A+ = Na, K, Rb, NH4, H3O, Ag, Tl and M3+ = Fe, Cr, V. In
condensed matter physics Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the sub ...
and materials science they are renowned for containing layers with
kagome lattice In geometry, the trihexagonal tiling is one of 11 uniform tilings of the Euclidean plane by regular polygons. See in particular Theorem 2.1.3, p. 59 (classification of uniform tilings); Figure 2.1.5, p.63 (illustration of this tiling), Theorem 2. ...
structure, relating to
geometrically frustrated magnet In condensed matter physics, the term geometrical frustration (or in short: frustration) refers to a phenomenon where atoms tend to stick to non-trivial positions or where, on a regular crystal lattice, conflicting inter-atomic forces (each one favo ...
s.


See also

* Alunite *
Iron(III) sulfate Iron(III) sulfate (or ferric sulfate), is a family of inorganic compounds with the formula Fe2(SO4)3(H2O)n. A variety of hydrates are known, including the most commonly encountered form of "ferric sulfate". Solutions are used in dyeing as a morda ...
* Spirit Mars rover final embedding event


References

{{reflist * Palache C., Berman H., and Frondel C. (1951) Dana's system of mineralogy, (7th edition), v. II, 560–562.
Webmineral data


* ttp://news.discovery.com/history/archaeology/mysterious-spheres-emerge-from-ancient-temple-1304291.htm Discovery News (2013) "Robot Finds Mysterious Spheres in Ancient Temple"


External links


Further information about the Jaros Hydrothermal system
Iron(III) minerals Potassium minerals Alunite group Trigonal minerals Minerals in space group 166