Pascoite is a

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. ( ...

with formula Ca₃V₁₀O₂₈·17H₂O that is red-orange to yellow in color. It was discovered in the

Pasco Province The Pasco Province is one of the three provinces that make up the Pasco Region in Peru. The capital of this province is the city Cerro de Pasco. Boundaries *North: Huánuco Region *East: Oxapampa Province *South: Junín Region *West: Lima Regio ...

of Peru, for which it is named, and described in 1914.

Description

Crystals of pascoite, which occur in granular crusts, are minute and lath-like with oblique terminations. The mineral is dark red-orange to yellow-orange in color and dirty yellow when partially dehydrated. It occurs as

efflorescence In chemistry, efflorescence (which means "to flower out" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or ...

s in mine tunnels or as a product leached out of surficial

vanadium oxide Vanadium oxide may refer to: * Vanadium(II) oxide (vanadium monoxide), VO * Vanadium(III) oxide (vanadium sesquioxide ''or'' trioxide), V2O3 * Vanadium(IV) oxide (vanadium dioxide), VO2 * Vanadium(V) oxide (vanadium pentoxide), V2O5 * Vanadium(VI ...

s by

ground water 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 ...

. Pascoite has been found in association with

carnotite Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula K2( U O2)2( VO4)2·3 H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present. Occurrence Carnotite i ...

. Pascoite melts readily to form a deep red liquid. Pascoite is a member of the eponymous pascoite group. 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 is

magnesiopascoite Magnesiopascoite is a bright orange mineral with formula Ca2Mg(V10O28)·16H2O. It was discovered in the U.S. state of Utah and formally described in 2008. The mineral's name derives from its status as the magnesium analogue of pascoite. Descripti ...

Structure

A 2005 study determined that pascoite has a C 2/m disordered

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

. It consists of decavanadate anions (V₁₀O₂₈)⁶⁻ linked together by the

interstitial An interstitial space or interstice is a space between structures or objects. In particular, interstitial may refer to: Biology * Interstitial cell tumor * Interstitial cell, any cell that lies between other cells * Interstitial collagenase, ...

complex ⁶⁺.

Synthesis

Pascoite can be easily synthesized by leaching oxides of

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 to ...

and vanadium with water to produce an orange-colored

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...

with an pH of about 4.6. Evaporation of the solution at room temperature produces orange-red crystals of the mineral. Dissolved pascoite can also be recrystallized from water.

History

Pascoite was discovered in the Ragra mine near

Cerro de Pasco Cerro de Pasco is a city in central Peru, located at the top of the Andean mountains. It is the capital of the Pasco region, and an important mining center. At elevation, it is one of the highest cities in the world, and the highest or the sec ...

, Peru, where the mineral formed on the walls of an exploratory tunnel after its excavation. The specimens were transported by D. Foster Hewett from Peru to the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

laboratory for analysis. Several years later, in 1914, pascoite was described in the ''

Proceedings of the American Philosophical Society ''Proceedings of the American Philosophical Society'' is a quarterly journal published by the American Philosophical Society since 1838. The journal contains papers which have been read at meetings of the American Philosophical Society each April ...

''. It was named for the

in which it was discovered.

Distribution

Pascoite has been found in Argentina, the Czech Republic, Italy, Peru, the UK and the US. Several of the sites from which it has been reported are

uranium mining Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account f ...

districts. The

type material In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes t ...

is held in the United States at

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

in Massachusetts and the

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...

in Washington, D.C.

References

;Citations ;Bibliography * * * *

External links

{{commonscat-inline, Pascoite Monoclinic minerals Minerals in space group 12 Calcium minerals Vanadate minerals Hydrates Minerals described in 1914