Magnesiopascoite is a bright orange mineral with formula Ca₂Mg(V₁₀O₂₈)·16H₂O. It was discovered in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

and formally described in 2008. The mineral's name derives from its status as the

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

analogue of pascoite.

Description

Magnesiopascoite is a member of the pascoite group and is the magnesium analogue of pascoite. It is transparent and bright orange in color, occurring as intergrown, parallel stackings of crystals up to several millimeters in the largest dimension. The crystals vary from tabular to

equant Equant (or punctum aequans) is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of the planets. The equant is used to explain the observed speed change in different stages of the plane ...

to prismatic. The mineral dissolves slowly in water and quickly in cold, dilute

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

. It decomposes rapidly when mildly heated, likely as a result of

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. Mil ...

Structure and composition

The

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...

of magnesiopascoite consists of the decavanadate anion (V₁₀O₂₈)⁶⁻ and interstitial ⁶⁺ consisting of Mg(H₂O)₆ octahedra and seven-fold coordinated CaO₂(H₂O)5. The structure differs from that of pascoite primarily in cation coordination in the interstitial complex. In addition to

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

and magnesium, magnesiopascoite contains minute quantities 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

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, p ...

History

Joe Marty discovered specimens of magnesiopascoite in

San Juan County, Utah San Juan County ( ) is a county in the southeastern portion of the U.S. state of Utah. As of the 2010 United States Census, the population was 14,746. Its county seat is Monticello, while its most populous city is Blanding. The Utah State Legi ...

, in the Blue Cap mine and the nearby Vanadium Queen mine. The mineral was named "magnesiopascoite" because it is the magnesium analogue of pascoite. The mineral and name were approved by the IMA Commission on New Minerals, Nomenclature and Classification (IMA 2007-025). Magnesiopascoite was described in 2008 in the journal ''Canadian Mineralogist''. The two cotype specimens are held at the

Natural History Museum of Los Angeles County The Natural History Museum of Los Angeles County is the largest natural and historical museum in the western United States. Its collections include nearly 35 million specimens and artifacts and cover 4.5 billion years of history. This large col ...

in the US State of California.

Occurrence

In the area of the type locality, the reducing environment caused by

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

aceous material in the Salt Wash and Brushy Basin members of the Morrison Formation precipitated

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

and vanadium minerals from solution. After mining, subsequent

leaching Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to: * Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amou ...

and oxidation by

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...

created magnesiopascoite. The mineral has been found in association with

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywal ...

, martyite, montroseite,

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 ...

and rossite.

References

Bibliography

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External links

Photos of magnesiopascoite
from Mindat.org Monoclinic minerals Minerals in space group 12 Calcium minerals Magnesium minerals Vanadate minerals Hydrates Minerals described in 2008