684 



UNITED STATES MINERAL RESOURCES 



stratigraphic zone over broad areas. It is generally 

 assumed that the vanadium and associated metals 

 were introduced by ground waters moving along the 

 sandstone host beds to places where an adequate 

 reducing environment existed ; coalified plant ma^ 

 terial and H^S generated by bacteria feeding on the 

 plant material likely were the reducing agents. 



ASPHALTITE DEPOSITS 



The trace amounts of vanadium in crude oils tend 

 to accumulate in the natural asphalts and related 

 materials that are the residues or natural distillation 

 products of crude oils. Many asphaltites contain 

 about 1 percent V2O5, and some have yielded samples 

 reported to contain appreciably more vanadium. 

 One asphaltite deposit, that at Mina Ragra, Peru 

 (McKinstry, 1957), has been intensively exploited 

 for vanadium ; this deposit was mined from 1907 to 

 1955 and was the world's principal source of va- 

 nadium in the early 1900's. Unoxidized ore in this 

 deposit consisted of quisqueite (a hydrocarbon) , 

 coke, and patronite (a vanadium sulfide). Vanadates 

 and vanadium oxide minerals formed the near- 

 surface oxidized ore, some of which was fabulously 

 rich, containing as much as 40 percent V2O5. Coun- 

 try rock at Mina Ragra comprises shale and thin- 

 bedded limestone of Cretaceous age. These rocks 

 were invaded by igneous dikes and were cut by num- 

 erous faults. The ore minerals and associated ma- 

 terial occupy a fracture and permeate the adjoining 

 shale, forming a lens-shaped body, about 50 feet wide 

 and several hundred feet long at the surface, which 

 bottomed at a depth of about 250 feet. The high con- 

 centration of vanadium in this deposit may be due 

 to intensive distillation of the original asphaltite and 

 perhaps to a local transfer of vanadium from the 

 country rock by thermal solutions. 



DEPOSITS ASSOCIATED WITH 

 ALIL\LIC IGNEOUS COMPLEXES 



The recently developed vanadium deposit at Wil- 

 son Springs, Ark., is at the contact of the Potash 

 Sulfur Springs alkalic intrusive complex (Hollings- 

 worth, 1967). The vanadium ore, which contains 

 about 1 percent V2O5, occurs as poorly defined 

 bodies in irregular masses of argillic altered rock of 

 both the igneous intrusion and the bordering sedi- 

 mentary strata. For mining control, ore bodies are 

 delimited by assaying samples ; recognizable vanadi- 

 um minerals are sparse. A similar deposit occurs at 

 the contact of the nearby Magnet Cove alkalic com- 

 plex (Reed, 1949). 



Because of the intensive alteration of the host 

 rocks and deep weathering in the area, the genesis of 



these deposits is not yet clearly established; ulti- 

 mately, these deposits may be classified as either 

 contact metasomatic or hydrothermal. But regard- 

 less of the mode of concentration, the significant 

 factor in the origin of these deposits may be their 

 association with alkalic igneous complexes. Although 

 this association has not been recognized by most 

 students of the geochemical distribution of vanadi- 

 um, anomalous amounts of vanadium are reported in 

 analyses of samples from numerous alkalic igneous 

 complexes in various parts of the world. Magnetite 

 and titanium minerals, especially ilmenite, are com- 

 mon in many alkalic intrusives, and vanadium is 

 commonly associated with these minerals in the 

 magmatic stage and to some extent in hydrothermal 

 deposits. If these ideas are correct, alkalic intrusives 

 should be searched more frequently for vanadium 

 deposits. Exploration probably will be difficult, how- 

 ever, for the vanadium probably will not occur in 

 visually recognizable minerals. 



RESOURCES 



World resources of vanadium in known deposits 

 are very large (Fischer, 1961). They amount to mil- 

 lions of short tons V, representing hundreds of 

 years' supply at the current rate of consumption. 

 Only a few known deposits, however, are rich 

 enough in vanadium to be worked for this metal 

 alone. Most of the vanadium resources are in de- 

 posits from which vanadium is being, and will be, 

 recovered as a coproduct or byproduct. Some pro- 

 ductive sources contain only trace amounts of va- 

 nadium, which is recovered only as a minor byprod- 

 uct from waste materials. 



RESERVES IN PRODUCTIVE DEPOSITS 



Significant data on the major and most of the 

 minor sources of vanadium in 1970 are summarized 

 in table 147. This table shows the known reserves in 

 certain deposits, and it also illustrates the diverse 

 geologic materials from which vanadium can be re- 

 covered and the ranges in grade of these materials, 

 factors that are important in estimating future pro- 

 duction and potential resources in unproductive 

 deposits. 



POTENTIAL RESOURCES IN UNPRODUCTIVE 

 DEPOSITS 



Large vanadium resources occur in known but un- 

 productive deposits similar to those from which 

 vanadium is being recovered. (In this discussion, 

 "large" implies more than about 1,000,000 short tons 

 V, "moderate" from about 100,000 to 1,000,000 short 

 tons, and "small" less than about 100,000 short tons.) 

 Large resources also occur in carbonaceous shale 



