Jarosite is a basic
hydrous 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 ...
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 atmosph ...
and ferric
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 group 8 element, group 8 of the periodic table. It is, Abundanc ...
(Fe-III) with a chemical formula of KFe
3(SO
4)
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 ...
of iron
sulfides. 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 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 crystal ...
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 at its densest ...
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 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 wor ...
series. The alunite supergroup has the general formula AB
3(TO
4)
2(OH)
6. In the alunite subgroup B is Al, and in the jarosite subgroup B is Fe
3+. The beudantite subgroup has the general formula AB
3(XO
4)(SO
4)(OH)
6, the crandallite subgroup AB
3(TO
4)
2(OH)
5•H
2O and the florencite subgroup AB
3(TO
4)
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, KAl
3(SO
4)
2(OH)
6, probably exists, but intermediate members are rare. The material from
Kopec,
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 Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.
Pyrite's metallic luster and pale brass-yellow hue giv ...
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 ...
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. In other geological settings
mica'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 NaFe
3(SO
4)
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. 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
hydroniumjarosite[American 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 i ...
ion H
3O
+ 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, Pb
2+Al
3(PO
4)
2(OH)
5.H
2O, which is a member of the crandallite subgroup.
:Secondly by incorporating divalent ions in the B sites, as in
osarizawaite, Pb
2+Cu
2+Al
2(SO
4)
2(OH)
6, alunite subgroup, and
beaverite, Pb
2+Cu
2+(Fe
3+,Al)
2(SO
4)
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 ...
, PbFe
3+3(AsO
4)
3−(SO
4)(OH)
6, beudantite subgroup.
History
Jarosite was first described in 1852 by
August Breithaupt 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 g ...
,
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'' 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 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
* ...
'' 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. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
. 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 overl ...
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 cont ...
. 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 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 AM
3(OH)
6(SO
4)
2, where A
+ =
Na,
K,
Rb,
NH4,
H3O,
Ag,
Tl and M
3+ =
Fe,
Cr,
V. In
condensed matter physics and
materials science they are renowned for containing layers with
kagome lattice 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