VANADIUM 



681 



1930 



1950 



1970 



1910 



Figure 75 .- — Generalized graph showing the principal geo- 

 graphic sources of vanadium, 1910-70. Data from pub- 

 lished figures of U.S. Geological Survey (1910 and 1920) 

 and U.S. Bureau of Mines, except U.S.S.R. data for 1960 

 and 1970, which are estimates by the writer. 



1910 



1930 



Figure 76. — Generalized graph showing the principal geologic 

 types of deposits from which vanadium was recovered, 

 1910-70. Compilation by author, based on data in figure 75 . 



rest is from phosphate rock and the deposit in 

 Arkansas described below. The category "Iron 

 deposits" is wholly from titaniferous magnetite 

 deposits. The vanadium produced in 1970 from coun- 

 tries other than those shown in figure 75 (see "Geo- 

 graphic Sources of Vanadium") was derived from 

 iron ores, the residue of petroleum refining, the soot 

 and ash from furnaces burning crude oil, the sludge 

 derived from the Bayer process of making alumina, 

 and other waste products. 



About 75 percent of the reported and estimated 



1970 vanadium production shown in figure 76 was 

 derived from iron (titaniferous magnetite) deposits. 

 Output from this source became significant in the 

 1950's and large in the 1960's, reflecting the inability 

 of the traditional high-grade sources to satisfy the 

 increasing requirements for vanadium. This situation 

 is analogous to that of the copper industry about 50 

 years ago, when copper requirements exceeded the 

 capacity of the high-grade sources, mainly vein de- 

 posits, to meet the demands, and the large-tonnage, 

 low-grade porphyry copper deposits were developed 

 as the principal geologic source of copper. 



GEOLOGIC ENVIRONMENT 

 GEOCHEMISTRY 



Vanadium is considered to be a minor element, but 

 it is a rather abundant one. Its crustal abundance is 

 in the order of 100-150 ppm (parts per million), 

 about twice that of copper and zinc and 10 times that 

 of lead. It is one of the lithophile elements that occur 

 mainly in silicate rocks, but it does not form an im- 

 portant part of any common rock-forming mineral. 

 It also has a biophile tendency, so it accumulates in 

 some environments rich in organic materials. Va- 

 nadium occurs in three valence states in nature; 3- 

 and 4-valent vanadium are rather insoluble in aque- 

 ous solutions, but 5-valent vanadium is relatively 

 soluble. 



Geologically, vanadium is a rather well-disciplined 

 element — it has a well-defined geochemical cycle, and 

 it accumulates in only a small number of geologic 

 situations, where its habits and grade range are 

 reasonably consistent. 



In igneous rocks, vanadium occurs mainly in the 

 insoluble 3-valent state and substitutes for iron and 

 perhaps aluminum in iron and ferromagnesian min- 

 erals. It is most abundant in the mafic igneous rocks 

 (about 200 ppm) , less abundant in the ultramafic and 

 intermediate rocks (about 50 ppm) , and sparse in the 

 silicic ones (about 25 ppm). Vanadium is concen- 

 trated in magmatic magnetite deposits, especially 

 those that are titaniferous, and commonly ranges 

 from 1,000 to 5,000 ppm in these deposits. 



Because most of the vanadium in magmas is in the 

 insoluble 3-valent state, not much vanadium is avail- 

 able for hydrothermal transport ; hence, only a little 

 (10-100 ppm V) occurs in most hydrothermal ore 

 deposits. However, many titanium-bearing vein de- 

 posits and some gold-quartz veins, especially those 

 with gold-telluride minerals, contain some vanadium, 

 commonly about 1,000 ppm. 



During weathering of igneous rocks in humid cli- 

 mates, much of the vanadium in the ferromagnesian 



