Minerals vanadinite

Vanadium is not found in its pure state. Small amounts of vanadium can be found in phosphate rocks and some iron ores. Most of it is recovered from two minerals vanadinite, which is a compound of lead and chlorine plus some vanadium oxide, and carnotite, a mineral containing uranium, potassium, and an oxide of vanadium. Because of its four oxidation states and its ability to act as both a metal and a nonmetal, vanadium is known to chemically combine with over 55 different elements. 

Now we know that Del Rio s brown lead from Zimapan was the mineral vanadinite, Pb5[Cl(VOj3] (Figure M31). 

Vanadium is found in about 65 different minerals among which are carnotite, roscoelite, vanadinite, and patronite, important sources of the metal. Vanadium is also found in phosphate rock and certain iron ores, and is present in some crude oils in the form of organic complexes. It is also found in small percentages in meteorites. 

Minerals can form colorful regular crystals. Shown here are vanadinite, Pbj (V04)3 Cl lefty, quartz, Si02 center)-, fluorapatite, Caj (P04)3 F top right)-, and stibnite,... 

Occurrence. Important minerals are carnotite K(U02)V04 3/2 H20, more important as a uranium ore, vanadinite Pb5(V04)3Cl and some complex sulphides. It occurs also in certain crude oils and may be recovered from dusts after combustion. 

Natural fibrous materials are identified somewhat by chance. For example, there are seven vanadate and seven vanadium oxysalt minerals on the list of fibrous minerals. These species are composed of a rare element, vanadium, but the fibrous samples may have attracted attention because they are often brightly colored. Vanadinite [Pb5(V04)3Cl] for example, is bright orange-red. Further, the list of natural mineral fibers we have compiled contains seventy-seven phosphate species. So many phosphates are listed because detailed descriptions of these mostly quite rare minerals were readily available (Nriagu and Moore, 1984). 

VANADINITE. The mineral vanadimte corresponds to the formula Pb VO Cl, being composed of lead chloride and lead vanadate in the proportion of 90.2% of the former and 9.8% of the latter. It crystallizes in the hexagonal system, is usually prismatic, but the ciystals are often skeletal or cavernous it may be found in crusts. Its fracture is uneven brittle hardness. 2.75-3 specific gravity. 6.86 fresh fractures show a resinous luster color, yellow, yellowish-brown, reddish-brown, and red streak, white to yellowish translucent to opaque. Vanadinite, not a common mineral, occurs as an alteration product in lead deposits. It is found in the Ural Mountains, Austria, Spain, Scotland, Morocco, the Transvaal, Argentina, and Mexico, In the United States it occurs in Arizona, New Mexico, and South Dakota, It is used as an ore of vanadium and to some extent of lead as well. It is interesting to note that this mineral was first described as a chromate upon its discovery in Mexico in 1801, It was not until the discovery of the element vanadium in 1830 that the true nature of this compound was known. 

Vanadium is the most important element of group Va. It finds extensive use in the manufacture of special steels. Vanadium steel is tough and strong, and is used in automobile crank shafts and for similar purposes. The prineipkl ores of vanadium are vanadinite, Pb5(V04)3CI, and carnoiite, K(U02)V04 H20. The latter mineral is also important as an ore of uranium. 

Lead is a heavy soft bluish-gray metal (symbol Pb atomic no. 82) that is widespread as different salts in minerals such as chromite (oxide), crocoisite (chromate), Jamesonite and zinkenite (sulfides), mimetite (arsenate and chloride), pyromorphite (phosphate and chloride), and vanadinite (vanadate and chloride). 

Vanadium is found in minerals such as vanadinite. lAAAGE COPYRIGHT 2009, RICHARD KITTENBERGER. USED UNDER LICENSE FROM SHUTTERSTOCK.COM. 

Vanadium is found in a number of minerals, including vanadinite (see photo on page 651), carnotite, roscoelite, and patronite. 

Vanadium is widely, but sparsely, distributed in the earth s crust (Byerrum et al. 1974 Windholz 1983). It may be found at levels as great as 0.07% in the lithosphere and exists in the form of over 50 different mineral ores (Grayson 1983). The principal ores are carnotite, patronite, roscoelite, and vanadinite (Grayson 1983 Byerrum et al. 1974 Weast 1969 Windholz 1983). Vanadium is also found in phosphate rock, some iron ores, and crude petroleum deposits. Flue-gas deposits from oil-fired furnaces have been found to contain up to 50% vanadium pentoxide (Brooks 1986 Grayson 1983 Symanski 1983 Weast 1969). 

Vanadinite, 3 Pb3(V04)2 PbCl2 or (PbCl)Pb4(V04)3, is the mineral from which Del Rio first obtained vanadium material. It contains from 8 to 21 per cent V20 6, varies in color from deep ruby red to a straw yellow, and is found in Mexico, Urals, Sweden, Argentina, and abundantly in the mining regions of Arizona and New Mexico. 

Vanadium is the nineteenth element in abundance (136 ppm) and the fifth most abundant transition element in Earth s crust. It is found in approximately sixty-five different minerals (such as roscoefite and vanadinite), phosphate rock, iron ores, and some crude oils as organic complexes. Since there are few concentrated deposits of vanadium compounds, it is obtained as a coproduct of refining. The element has two naturally occurring isotopes °V (0.25%) and (99.75%). 

Vanadium has an abundance in Nature of about 0.02%. It is widely spread but there are few concentrated deposits. Important minerals are patronite (a complex sulfide), vanadinite [Pb5(V04)3Cl], and carnotite [K(U02)V04.> fH20]. The last of these is more important as a uranium ore, but the vanadium is usually recovered as well. Vanadium also occurs widely in certain petroleums, notably those from Venezuela, and it can be isolated from them as oxovanadium(iv) porphyrins.1 V2Os is recovered from flue dusts after combustion. 

Rammelsberg in 1856 had shown that vanadinite and pyro-morphite are isomorphous. Roscoe pointed out that if Mitscherlich s Law of Isomorphism applied, the two minerals ought to possess analogous structures. This could only be the case if vanadium had the same valency as phosphorus. In that case vanadium would be pentavalent like nitrogen and phosphorus, not hexavalent like chromium and uranium. The two minerals would thus be represented as follows —... 

It exists as a sulfide or in the oxidized form. Of the 60 known vanadium minerals, only patronite (V2S5), roscoelite (K(A1, V)2-[AlSi2 Oio]-(OH, F)2), carnotite (KUO2-VO4 1.5 H2O) and vanadinite [Pb5(V04)3Cl] are commercial sources of vanadium. In none of these ores is vanadium present at more than 3% content. 

Dai Y, Hughes JM (1989) Crystal structure refinements of vanadinite and pyromorphite. Can Mineral 27 189-192... 

Curry NA, Jones DW (1971) Crystal structure of brashite, calcium hydrogen orthophosphate dihydrate A neutron-diffraction investigation. J Chem Soc 3725-3729 Dai Y, Hughes JM (1989) Crystal-structure refinements of vanadinite and pyromorphite. Can Mineral 27 189-192... 

Vanadinite Pb5(V04)3Cl is generally a strongly colored mineral that rarely shows fluorescence, but the weakest colored varieties, straw-yellow in physical color, can show yellow or greenish-yellow emission. Robbins (1994) notes that such vanadinite from Santa Eulalia, Chihuahua, Mexico is probably endlichite, with a large amount of arsenate substituting for vanadate. 

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