Meridianiite is 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. Rafferty, ed. ...

consisting of

magnesium sulfate Magnesium sulfate or magnesium sulphate (in English-speaking countries other than the US) is a chemical compound, a salt with the formula , consisting of magnesium cations (20.19% by mass) and sulfate anions . It is a white crystalline sol ...

undecahydrate, . It is colorless transparent crystalline salt that precipitates from solutions saturated in Mg²⁺ and SO₄²⁻ ions at temperatures less than 2 °C. The synthetic compound was formerly known as Fritzsche's salt. Meridianiite is a naturally occurring

species found on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

in a variety of environments including sea ice, crusts and efflorescences in coal/metal mines, cave systems, oxidized zones of sulfide deposits, salt lakes/playas and Antarctic ice-cores. It is commonly associated with other

evaporite An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...

minerals such as

epsomite Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O. Epsomite crystallizes in the orthorhombic system as rarely found acicular or fibrous crystals, the normal form is as massiv ...

mirabilite Mirabilite, also known as Glauber's salt, is a hydrous sodium sulfate mineral with the chemical formula Na2SO4·10H2O. It is a vitreous, colorless to white monoclinic mineral that forms as an evaporite from sodium sulfate-bearing brines. It is fo ...

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a f ...

s, and other sodium-magnesium-sulfates. There is some evidence that it was once present on 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 atm ...

, and may occur in several bodies of the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

. As of 2012, it was the only undecahydrate sulfate known.

Properties

Meridianiite belongs to the

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal is ...

crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their poi ...

, having cell parameters a = 6.7459 Å, b = 6.8173 Å, c = 17.299 Å, a

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematica ...

= 1.512 g/cm³, x-ray diffraction peaks at d-spacings = 5.73, 5.62, 5.41, 4.91, 4.85, 2.988, 2.958 (highest intensity), and 2.940, and is IR active. It produces needle-shaped to broad flat crystals that are clear to colorless-white. Meridianiite decomposes incongruently above 2 °C to produce

(MgSO₄·7H₂O) and

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. Meridaniite and water have a eutectic point at −3.9 °C and 17.3% (mass) of MgSO₄. Meridianiite can incorporate large proportions of other divalent cations (whose sulfates themselves do not seem to form an undecahydrate) as solid solution, without changes to its structure. These include

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

(up to about 27% of the cations replaced),

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 periodic t ...

(up to about 27%),

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, ...

(up to about 67%), manganese(II) (about 62%),

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish- ...

(about 8%), and

iron(II) In chemistry, iron(II) refers to the element iron in its +2 oxidation state. In ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe2+. The adjective ferrous or the prefix ferro- is often used to sp ...

(about 8%). At pressures of about 0.9

GPa Grading in education is the process of applying standardized measurements for varying levels of achievements in a course. Grades can be assigned as letters (usually A through F), as a range (for example, 1 to 6), as a percentage, or as a numb ...

and at 240 K, meridianiite decomposes into a mixture of

ice VI Ice VI is a form of ice that exists at high pressure at the order of about 1 GPa (= 10 000 bar) and temperatures ranging from 130 up to 355 Kelvin (−143 °C up to 82 °C); see also the phase diagram of water. Its discovery and th ...

and the enneahydrate ,

Discovery

In 1837 by C. J. Fritzsche described what he interpreted as magnesium sulfate dodecahydrate, based on the weight loss during

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mi ...

to the anhydrous salt. The substance was referred to as "Fritzsche's salt" and not formally given a mineral name or designation. The crystal structure was later resolved by Peterson and Wang in 2006, revealing that it belonged to the

crystal system, and each formula unit included 11 molecules of water, not 12. The name "meridianiite" is derived from

Meridiani Planum The Meridiani Planum (alternately Meridiani plain, Meridiani plains, Terra Meridiani, or Terra Meridiani plains) is either a large plain straddling the equator of Mars and covered with a vast number of spherules containing a lot of iron oxide or ...

, the locality on Mars where it is believed to have existed in the past. The mineral species and the name were approved by the Commission on New Mineral Names and Mineral Nomenclature of the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...

in November 2007.

Occurrence on Earth

Meridianiite has been found to occur on the surface of the ice layer formed in winter over the ponds known as Basque Lakes, in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world ...

. The water in those ponds has a high concentration of magnesium sulfate and other salts. Water seeping through the ice layer evaporates at the surface leaving a deposit of crystalline meridianiite. Meridianiite has also been detected in sea-ice collected in winter from the saline

Lake Saroma , also Saroma Lagoon, is a coastal lagoon (hence a body of brackish water) in Saroma, Kitami, and Yūbetsu Hokkaidō, Japan. It is located in Abashiri Quasi-National Park. By area, the lake is the third largest in Japan and the largest in Hokk ...

in Japan, as well as in ice cores from Dome Fuji station,

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 ...

, near the summit of the east Dronning Maud Land plateau.

Extraterrestrial occurrence

Imagery of the massive sulfate deposits sent back by the

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding ...

''Opportunity'' rover in Meridiani Planum show numerous needle-shaped void spaces throughout the deposit. The now empty angular holes are interpreted as being cavities once filled by a highly soluble mineral species, most likely a magnesium sulfate. These cavities are observed to closely match the crystal habit of meridianiite, and have been proposed as sites where crystals of meridianiite were located, having subsequently dissolved when environmental conditions rendered the crystal unstable. Due to the decomposition of meridianiite to 70%

and 30%

, it has been proposed that meridianiite may represent a periodic reservoir of water near the Martian surface. During warmer periods in Mars’ history it is possible that triggered melting of this mineral may help explain the occurrence of some of the chaotic, and short lived, surface-water episodes throughout Martian history.

Remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about E ...

of other planetary bodies has also indicated the presence of numerous hydrated mineral species, including sulfates, near various planetary surfaces, a prominent example of which is

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

’s moon Europa. The relatively smooth, and very young surface of Europa has been interpreted as evidence for a putative ocean beneath the moons icy surface, and is therefore suggestive of liquid brine at depth. Due to the cryospheric conditions present on Europa it is likely that any magnesium sulfate minerals present, and in contact with liquid water, would inherently occur as meridianiite, and thus, it may make up an important mineral phase, and liquid water reservoir at depth.

Gallery

Image:Meridianiite Crystal Forms.jpg, Figure 1. (a, b, d) Optical images of meridianiite, MgSO₄•11H₂O. Courtesy Genceli et al. 2007. Image:Meridianiite Type Locality.jpg, Figure 2. Sampling of meridianiite off a wooden post. Courtesy R. Peterson 2010. Image:Meridianiite on a Wooden Post.jpg, Figure 3. Type occurrence of meridianiite at Basque Lake No. 1. Courtesy R. Peterson 2010. Image:Meridianiite4.jpg, Figure 4. Meridianiite mineral type locality; Basque Lake No. 1 as seen in winter 2007. Courtesy R. Peterson 2010. Image:Mineral Voids in Martian Sulfates.jpg, Figure 5. Long needle-shaped crystal void cavities as observed by the NASA Opportunity Rover at Meridiani Planum, Mars. Image courtesy R. Peterson 2010, and NASA. Image:Meridianiite6.jpg, Figure 6. Temperature vs. weight % MgSO₄ diagram depicting the stability ranges of the various pure magnesium sulfate hydrated salts. Courtesy R. Peterson 2010. Image:Meridianiite7.jpg, Figure 7. X-Ray diffraction data obtained using a Cobalt source for the magnesium sulfate hydrate, Meridianiite. The dotted line is representative of the ideal intensity and spectral pattern of meridianiite. Courtesy R. Peterson 2010. Image:Meridianiite IR Spectra.jpg, Figure 8. Infrared absorption of meridianiite. Courtesy R. Peterson 2010.

References

A. Dominic Fortes, Kevin S. Knight, and Ian G. Wood (2017): "Structure, thermal expansion and incompressibility of MgSO4·9H2O, its relationship to meridianiite (MgSO4·11H2O) and possible natural occurrences". ''Acta Crystallographica Section B: Structureal Science, Crystal Engineering and Materials'', volume 73, part 1, pages 47-64. C. J. Fritzsche (1837): "Ueber eine neue Verbindung der schwefelsauren Talkerde mit Wasser". ''Poggendorff's Annalen Der Physik Und Chemie'', now ''Annalen Der Physik'', volume 118, issue 12, pages 577–580. R. C. Peterson, W. Nelson, B. Madu, and H. F. Shurvell (2007): "Meridianiite: A new mineral species observed on Earth and predicted to exist on Mars". ''American Mineralogist'', volume 92, issue 10, pages 1756–1759. F. E. Genceli, S. Horikawa, Y. Iizuka, S. Toshimitsu, T. Hondoh, T. Kawamura, and G-J. Witkamp (2009): "Meridianiite detected in ice". ''Journal of Glaciology'', volume 55, issue 189, pages 117–122.DOI: https://doi.org/ A. Dominic Fortes, Frank Browning, and Ian G. Wood (2012): "Cation substitution in synthetic meridianiite (MgSO4·11H2O) I: X-ray powder diffraction analysis of quenched polycrystalline aggregates". ''Physics and Chemistry of Minerals'', volume 39, issue , pages 419–441. {{doi, 10.1007/s00269-012-0497-9 F. E. Genceli, M. Lutz, A.L. Spek, and G-J. Witkamp (2007): "Crystallization and characterization of a new magnesium sulfate hydrate MgSO₄•11H₂O." ''Crystal Growth & Design'', 7, pages 2460–2466. J. B. Dalton (2003): "Spectral behavior of hydrated sulfate salts: Implications for Europa mission spectrometer design." ''Astrobiology'', 3, pages 771–784. R. C. Peterson and R. Wang (2006): "Crystal molds on Mars: Melting of a possible new mineral species to create Martian chaotic terrain". ''Geology'', 34, pages 957–960. A. D. Fortes, I. G. Wood, and K. S. Knight (2008). "The crystal structure and thermal expansion tensor of MgSO₄•11D₂O (meridianiite) determined by neutron powder diffraction". ''Physics and Chemistry of Minerals'', 35, pages 207–221. Magnesium minerals Sulfate minerals Triclinic minerals Minerals in space group 2