Vanadinite
Encyclopedia
Vanadinite is a mineral
belonging to the apatite
group of phosphate
s, with the chemical formula Pb
5(V
O
4)3Cl
. It is one of the main industrial ores of the metal vanadium
and a minor source of lead
. A dense, brittle mineral, it is usually found in the form of red hexagonal crystal
s. It is an uncommon mineral, formed by the oxidation of lead ore deposits such as galena
. First discovered in 1801 in Mexico
, vanadinite deposits have since been unearthed in South America, Europe, Africa, and other parts of North America.
climates and forms by oxidation
of primary lead minerals. Vanadinite is especially found in association with the lead sulfide, galena
. Other associated minerals include wulfenite
, limonite
, and barite
.
It was originally discovered in Mexico by the Spanish mineralogist Andrés Manuel del Río
in 1801. He called the mineral "brown lead" and asserted that it contained a new element, which he first named pancromium and later, erythronium. However, he was later led to believe that this was not a new element but merely an impure form of chromium. In 1830, Nils Gabriel Sefström
discovered a new element, which he named vanadium. It was later revealed that this was identical to the metal discovered earlier by Andrés Manuel del Río. Del Río's "brown lead" was also rediscovered, in 1838 in Zimapan, Hidalgo, Mexico
, and was named vanadinite because of its high vanadium content. Other names that have since been given to vanadinite are johnstonite and lead vanadate.
, pyromorphite
, descloizite, mottramite
, wulfenite
, cerussite
, anglesite
,
calcite
, barite
and various iron oxide
minerals.
Deposits of vanadinite are found worldwide including Austria
, Spain
, Scotland
, the Ural Mountains
, South Africa
, Namibia
, Morocco
, Argentina
, Mexico
, and the US states of Arizona
, Colorado
, New Mexico
, and South Dakota
.
Vanadinite deposits are found in over 400 mines across the world. Notable vanadinite mines include those at Mibladen
, Morocco
; Tsumeb
, Namibia
; Cordoba
, Argentina
; Sierra County
, New Mexico
; Gila County, Arizona
; and Touisset, Morocco.
lead ions at the corners of a regular octahedron
, with one of the lead ions provided by an adjoining vanadinite molecule. The distance between each lead and chlorine ion is 317 picometre
s. The shortest distance between each lead ion is 4.48 Å. The octahedron shares two of its opposite faces with that of neighbouring vanadinite units, forming a continuous chain of octahedrons. Each vanadium atom is surrounded by four oxygen atoms at the corners of an irregular tetrahedron
. The distance between each oxygen and vanadium atom is either 1.72 or 1.76 Å. Three oxygen tetrahedrons adjoin each of the lead octahedrons along the chain.
Crystals of vanadinite conform to a hexagonal
system of symmetry. This internal structure is often reflected in the hexagonal external shape of the crystals. The crystals are usually in the form of short hexagonal prisms, but can also be found as hexagonal pyramids, rounded masses or crusts. A unit cell
of vanadinite, the smallest divisible unit that possesses the same symmetry and properties, is in the form of a hexagonal prism. The unit cell of vanadinite is composed of two of its molecules and has the dimensions a
= 10.331 Å
and c = 7.343 Å), where a is the length of each side of the hexagon and c is the height of the prism. The volume of each unit cell of vanadinite, given by the formula V = a2c sin(60°), is 678.72 Å3.
group of phosphate
s, and forms a chemical series with the minerals pyromorphite
(Pb5(PO4)3Cl) and mimetite
(Pb5(AsO4)3Cl), with both of which it may form solid solution
s. Whereas most chemical series involve the substitution of metallic ions, this series substitutes its anion groups; phosphate (PO4), arsenate
(As
O4) and vanadate
(VO4). Common impurities of vanadinite include phosphorus
, arsenic
and calcium
, where these may act as an isomorphic substitute for vanadium. Vanadinite when containing a high amount of the arsenic impurity is known as endlichite.
Vanadinite is usually bright-red or orange-red in colour, although sometimes brown, red-brown, grey, yellow, or colourless. Its distinctive colour makes it popular among mineral collectors. Its streak
can be either pale yellow or brownish-yellow. Vanadinite may be transparent, translucent or opaque, and its lustre
can range from resin
ous to adamantine
. Vanadinite is anisotropic, meaning that some of its properties differ when measured along different axes. When measured perpendicular and parallel to its axis of anisotropy, its refractive indices
are 2.350 and 2.416 respectively. This gives it a birefringence
of 0.066.
Vanadinite is very brittle, producing small, conchoidal fragments when fracture
d. Its hardness is 3–4 on the Mohs scale
, about the same as a copper coin. Vanadinite is particularly heavy for a translucent mineral. It has a molar mass
of 1416.27 g
/mole
and its specific gravity
can range between 6.6 and 7.2 because of impurities.
and roscoelite
, vanadinite is one of the main industrial ores of the element vanadium
, which can be extracted by roasting
and smelting
. It is occasionally used as a source of lead. A common process for extracting the vanadium begins with the heating of vanadinite with salt
(NaCl) or sodium carbonate
(Na2CO3) at about 850 °C to produce sodium vanadate
(NaVO3). This is dissolved in water and then treated with ammonium chloride
to give an orange coloured precipitate of ammonium metavanadate
. This is then melted to form a crude form of vanadium pentoxide (V2O5). Reduction of vanadium pentoxide with calcium
gives pure vanadium.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
belonging to the apatite
Apatite
Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...
group of phosphate
Phosphate minerals
Phosphate minerals are those minerals that contain the tetrahedrally coordinated phosphate anion along with the freely substituting arsenate and vanadate...
s, with the chemical formula Pb
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
5(V
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
4)3Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
. It is one of the main industrial ores of the metal vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
and a minor source of lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
. A dense, brittle mineral, it is usually found in the form of red hexagonal crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s. It is an uncommon mineral, formed by the oxidation of lead ore deposits such as galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
. First discovered in 1801 in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, vanadinite deposits have since been unearthed in South America, Europe, Africa, and other parts of North America.
Origins
Vanadinite is an uncommon mineral, only occurring as the result of chemical alterations to a pre-existing material. It is therefore known as a secondary mineral. It is found in aridArid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
climates and forms by oxidation
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
of primary lead minerals. Vanadinite is especially found in association with the lead sulfide, galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
. Other associated minerals include wulfenite
Wulfenite
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".It crystallizes...
, limonite
Limonite
Limonite is an ore consisting in a mixture of hydrated iron oxide-hydroxide of varying composition. The generic formula is frequently written as FeO·nH2O, although this is not entirely accurate as limonite often contains a varying amount of oxide compared to hydroxide.Together with hematite, it has...
, and barite
Barite
Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...
.
It was originally discovered in Mexico by the Spanish mineralogist Andrés Manuel del Río
Andrés Manuel del Río
Andrés Manuel del Río Fernández was a Spanish–Mexican scientist and naturalist who discovered the chemical element vanadium.-Education:...
in 1801. He called the mineral "brown lead" and asserted that it contained a new element, which he first named pancromium and later, erythronium. However, he was later led to believe that this was not a new element but merely an impure form of chromium. In 1830, Nils Gabriel Sefström
Nils Gabriel Sefström
Nils Gabriel Sefström was a Swedish chemist. Sefström was a student of Berzelius and, when studying the brittleness of steel in 1830, he rediscovered a new chemical element, to which he gave the name vanadium....
discovered a new element, which he named vanadium. It was later revealed that this was identical to the metal discovered earlier by Andrés Manuel del Río. Del Río's "brown lead" was also rediscovered, in 1838 in Zimapan, Hidalgo, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, and was named vanadinite because of its high vanadium content. Other names that have since been given to vanadinite are johnstonite and lead vanadate.
Occurrence
Vanadinite occurs as a secondary mineral in the oxidized zone of lead-bearing deposits, the vanadium is leached from wall-rock silicates. Associated minerals include mimetiteMimetite
Mimetite, whose name derives from the Greek Μιμητής mimethes, meaning "imitator", is an arsenate mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name is a reference to mimetite's resemblance to the mineral pyromorphite...
, pyromorphite
Pyromorphite
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb53Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal planes, sometimes combined with narrow faces of a hexagonal...
, descloizite, mottramite
Mottramite
Mottramite is an orthorhombic mineral, PbCu, at the copper end of the descloizite group. It was formerly called cuprodescloizite or psittacinite .-References:***...
, wulfenite
Wulfenite
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".It crystallizes...
, cerussite
Cerussite
Cerussite is a mineral consisting of lead carbonate , and an important ore of lead. The name is from the Latin cerussa, white lead. Cerussa nativa was mentioned by Conrad Gessner in 1565, and in 1832 F. S. Beudant applied the name cruse to the mineral, whilst the present form, cerussite, is due to...
, anglesite
Anglesite
Anglesite is a lead sulfate mineral with the chemical formula PbSO4. It occurs as an oxidation product of primary lead sulfide ore, galena. Anglesite occurs as prismatic orthorhombic crystals and earthy masses, and is isomorphous with barite and celestine. It contains 74% of lead by mass and...
,
calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, barite
Barite
Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...
and various iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
minerals.
Deposits of vanadinite are found worldwide including Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, the Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
, Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, and the US states of Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
.
Vanadinite deposits are found in over 400 mines across the world. Notable vanadinite mines include those at Mibladen
Midelt
Midelt is a town in central Morocco, in the high plains between the Middle Atlas and High Atlas mountain ranges. With an estimated population of 44,780, Midelt serves as the commercial center of a large agricultural hinterland. It is also one of Morocco's principal cities for the mining of several...
, Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
; Tsumeb
Tsumeb
Tsumeb is a city of 15,000 inhabitants and the largest town in Oshikoto region in northern Namibia. Tsumeb is the home of the world-famous Tsumeb mine, and the "gateway to the north" of Namibia. It is the closest town to the Etosha National Park...
, Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
; Cordoba
Córdoba, Argentina
Córdoba is a city located near the geographical center of Argentina, in the foothills of the Sierras Chicas on the Suquía River, about northwest of Buenos Aires. It is the capital of Córdoba Province. Córdoba is the second-largest city in Argentina after the federal capital Buenos Aires, with...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
; Sierra County
Sierra County, New Mexico
-2010:Whereas according to the 2010 U.S. Census Bureau:*85.6% White*0.4% Black*1.7% Native American*0.4% Asian*0.0% Native Hawaiian or Pacific Islander*3.3% Two or more races*8.6% Other races*28.0% Hispanic or Latino -2000:...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
; Gila County, Arizona
Gila County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*76.8% White*0.4% Black*14.8% Native American*0.5% Asian*0.1% Native Hawaiian or Pacific Islander*2.0% Two or more races*5.4% Other races*17.9% Hispanic or Latino -2000:...
; and Touisset, Morocco.
Structure
Vanadinite is a lead chlorovanadate with the chemical formula Pb5(VO4)3Cl. It is composed (by weight) of 73.15% lead, 10.79% vanadium, 13.56% oxygen, and 2.50% chlorine. Each structural unit of vanadinite contains a chlorine ion surrounded by six divalentDivalent
In chemistry, a divalent ion or molecule has a valence of two and thus can form two bonds with other ions or molecules. An older term for divalent is bivalent....
lead ions at the corners of a regular octahedron
Octahedron
In geometry, an octahedron is a polyhedron with eight faces. A regular octahedron is a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex....
, with one of the lead ions provided by an adjoining vanadinite molecule. The distance between each lead and chlorine ion is 317 picometre
Picometre
A picometre is a unit of length in the metric system, equal to one trillionth, i.e. of a metre, which is the current SI base unit of length...
s. The shortest distance between each lead ion is 4.48 Å. The octahedron shares two of its opposite faces with that of neighbouring vanadinite units, forming a continuous chain of octahedrons. Each vanadium atom is surrounded by four oxygen atoms at the corners of an irregular tetrahedron
Tetrahedron
In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...
. The distance between each oxygen and vanadium atom is either 1.72 or 1.76 Å. Three oxygen tetrahedrons adjoin each of the lead octahedrons along the chain.
Hexagonal crystal system
In crystallography, the hexagonal crystal system is one of the 7 crystal systems, the hexagonal lattice system is one of the 7 lattice systems, and the hexagonal crystal family is one of the 6 crystal families...
system of symmetry. This internal structure is often reflected in the hexagonal external shape of the crystals. The crystals are usually in the form of short hexagonal prisms, but can also be found as hexagonal pyramids, rounded masses or crusts. A unit cell
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
of vanadinite, the smallest divisible unit that possesses the same symmetry and properties, is in the form of a hexagonal prism. The unit cell of vanadinite is composed of two of its molecules and has the dimensions a
Hexagonal crystal system
In crystallography, the hexagonal crystal system is one of the 7 crystal systems, the hexagonal lattice system is one of the 7 lattice systems, and the hexagonal crystal family is one of the 6 crystal families...
= 10.331 Å
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
and c = 7.343 Å), where a is the length of each side of the hexagon and c is the height of the prism. The volume of each unit cell of vanadinite, given by the formula V = a2c sin(60°), is 678.72 Å3.
Characteristics
Vanadinite is in the apatiteApatite
Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...
group of phosphate
Phosphate minerals
Phosphate minerals are those minerals that contain the tetrahedrally coordinated phosphate anion along with the freely substituting arsenate and vanadate...
s, and forms a chemical series with the minerals pyromorphite
Pyromorphite
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb53Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal planes, sometimes combined with narrow faces of a hexagonal...
(Pb5(PO4)3Cl) and mimetite
Mimetite
Mimetite, whose name derives from the Greek Μιμητής mimethes, meaning "imitator", is an arsenate mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name is a reference to mimetite's resemblance to the mineral pyromorphite...
(Pb5(AsO4)3Cl), with both of which it may form solid solution
Solid solution
A solid solution is a solid-state solution of one or more solutes in a solvent. Such a mixture is considered a solution rather than a compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase...
s. Whereas most chemical series involve the substitution of metallic ions, this series substitutes its anion groups; phosphate (PO4), arsenate
Arsenate
The arsenate ion is AsO43−.An arsenate is any compound that contains this ion. Arsenates are salts or esters of arsenic acid.The arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic or As[V]....
(As
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
O4) and vanadate
Vanadate
In chemistry, a vanadate is a compound containing an oxoanion of vanadium generally in its highest oxidation state of +5. The simplest vanadate ion is the tetrahedral, orthovanadate, VO43− anion, which is present in e.g. sodium orthovanadate and in solutions of V2O5 in strong base...
(VO4). Common impurities of vanadinite include phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
, arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, where these may act as an isomorphic substitute for vanadium. Vanadinite when containing a high amount of the arsenic impurity is known as endlichite.
Vanadinite is usually bright-red or orange-red in colour, although sometimes brown, red-brown, grey, yellow, or colourless. Its distinctive colour makes it popular among mineral collectors. Its streak
Streak (mineralogy)
The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus...
can be either pale yellow or brownish-yellow. Vanadinite may be transparent, translucent or opaque, and its lustre
Lustre (mineralogy)
Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....
can range from resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
ous to adamantine
Lustre (mineralogy)
Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....
. Vanadinite is anisotropic, meaning that some of its properties differ when measured along different axes. When measured perpendicular and parallel to its axis of anisotropy, its refractive indices
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
are 2.350 and 2.416 respectively. This gives it a birefringence
Birefringence
Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...
of 0.066.
Vanadinite is very brittle, producing small, conchoidal fragments when fracture
Fracture
A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...
d. Its hardness is 3–4 on the Mohs scale
Mohs scale of mineral hardness
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
, about the same as a copper coin. Vanadinite is particularly heavy for a translucent mineral. It has a molar mass
Molar mass
Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol...
of 1416.27 g
Gram
The gram is a metric system unit of mass....
/mole
Mole (unit)
The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value...
and its specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
can range between 6.6 and 7.2 because of impurities.
Uses
Along with carnotiteCarnotite
Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula: K222·3H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present.-Occurrence:...
and roscoelite
Roscoelite
Roscoelite is a green mineral from the mica group that contains vanadium.The chemical formula is K2AlSi3O102.Crystals of roscoelite take on the monoclinic form, and are from the 2/m point group....
, vanadinite is one of the main industrial ores of the element vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
, which can be extracted by roasting
Roasting (metallurgy)
Roasting is a step in the processing of certain ores. More specifically, roasting is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component. Often before roasting, the ore has already been partially purified, e.g. by froth...
and smelting
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...
. It is occasionally used as a source of lead. A common process for extracting the vanadium begins with the heating of vanadinite with salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
(NaCl) or sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
(Na2CO3) at about 850 °C to produce sodium vanadate
Sodium metavanadate
Sodium metavanadate is a yellow solid which is soluble in water. Its use is limited to its hygroscopic property. Its natural forms include mineral metamunirite and a dihydrate, munirite. Both are very rare, metamunirite is now known only from V- and U-bearing sandstone formations of...
(NaVO3). This is dissolved in water and then treated with ammonium chloride
Ammonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...
to give an orange coloured precipitate of ammonium metavanadate
Ammonium metavanadate
Ammonium metavanadate, NH4VO3, is a yellow crystalline solid which is water soluble inorganic acid that acts as insulin mimic. It functions as a catalyst to certain reactions and is known to have toxic effects in certain species. It has been found in slags and fly ash from coal burning which has...
. This is then melted to form a crude form of vanadium pentoxide (V2O5). Reduction of vanadium pentoxide with calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
gives pure vanadium.