Knowledge of causes and the geological sources of vanadium
By Danniel Oosterman, P.Geo
Geologists tend to like to drill down on things to get to the root of the matter. For every mined commodity sold you can be sure that at some early stage—before a given mine was a twinkle in someone’s eye—a geologist pored over the rocks and wondered what it all means, echoing perhaps the human spirit Raphael tried to convey with Aristotle and Plato arguing metaphysics as centerpieces among a bevvy of great minds in his fresco, “The School of Athens.” But geology is less metaphysics than it is applied science: observe, hypothesize, test, make conclusions, rinse and repeat, determine cause and effect. From this we have what most people see as inanimate, uninteresting, ubiquitous things we call ‘rocks,’ having been not only accounted for with their own meticulous taxonomical jargon by geologists, but theories have come forth on how they form, where they come from, so that a picture emerges that is as elegant as it is daunting. And so for every commodity that is mined out of the ground, a geological model exists as to why it is there: the host-rock type and how they came to form.
For the most common commodities these are well understood. There are enough gold deposits out there that they have been studied to the point where the models and geology are almost common parlance among investors, even if only in an abstract sense. If one mentions a Carlin-type gold deposit, an investor may not understand the finer points of what exactly it means, but they likely know that this type of deposit—by it’s namesake alone—represents a significant deposit type. Significant enough that a whole trend in Nevada, USA, has been named after it.
What about vanadium? Can you name such a well-known trend as the Carlin Trend? A vanadium deposit-type so prolific that by its mere mention it raises an eyebrow? Most people can’t. In fact, when I mention that I work on a vanadium project to a non-mining person I sometimes have to assure them I’m not working in Wakanda, and no we don’t make Captain America’s shield invincible. Although assuredly, if we were to add 0.5% of vanadium to that shield, it would probably double in strength and become 30% lighter. That is in fact one of the properties that is imbued to steel alloys when vanadium is added. It’s one of the reasons people are so interested in vanadium these days. So let’s then give a brief overview of where this amazing element comes from through a geological lens.
While vanadium occurs in trace amounts in most rocks, economic concentrations of vanadium occur four main types of mineral deposits. Fossil fuels represent another geological source of vanadium but will not be discussed here. These four types, in order of their abundance, vanadiferous titanomagnetite deposits, sandstone-hosted vanadium deposits, shale-hosted vanadium deposits, and vanadate deposits.
Other than being a mouthful, vanadiferous titanomagnetite deposits (“VTD”) are the premiere source of vanadium world wide. They are classed as igneous-hosted deposits, which is to say they come from deep magmatic processes earth that were intruded into the continental crust. In short: these are intrusions such as the world-famous Bushveld Complex, which is most famous for its prolific platinum and palladium mining. It also hosts one of the largest VTD deposits. The vanadium in these deposits is associated with specific minerals knowns as magnetite, an iron-oxide, and ilmenite, an iron-titanium oxide, and also a titanium oxide known as rutile. They typically grade between 0.2 and 1% V2O5 with higher grade deposits such as the Bushveld attaining grades over 2% V2O5.
One can be forgiven for splitting hairs on sandstone-hosted vanadium (“SSV”) deposits, as technically they are associated is known as sandstone-hosted uranium deposits. It’s both fish and fowl in some cases, and the USA’s Colorado Plateau is the main worldwide producer of this type of vanadium as a by-product of it’s uranium mining enterprise. Geochemically, uranium and vanadium solubility behave similarly according to the oxidation-reduction conditions to which they are subjected which is why this affinity is seen to occur. Unlike VTD deposits these are sedimentary rocks. With the sustained rise in vanadium prices since 2017 many uranium producers are seeking to prioritize this production. The vanadium (V%) grade in these deposits typically range between 0.1% and 1% vanadium.
Shale-hosted vanadium deposits are sedimentary rocks also commonly called black-shale vanadium deposits. Shales a greater proportion of clay minerals than the sandstones mentioned above. These deposits are often associated with phosphate deposits, and the black-shale association is because most of these deposits have high carbon content due to organic matter that settled into these rocks while they were loose sediments that eventually were buried and lithified, with the organic carbon imparting its black hue. Their genesis is not well understood however the association with organic material and clay minerals is well-documented with these deposits typically ranging between 0.2% and 2% V2O5. In rare cases, later processes can alter this association; at the Gibellini deposit in Nevada, USA, post-depositional processes of oxygen bearing fluids likely oxidized the upper portions of this deposit making it unique in terms of itsmineral assemblages with these oxidized zones having undergone a natural zone refining process—known as supergene enrichment—resulting in unique mineral assemblages. The USGS states that Gibellini is slated to be the first primary shale-hosted producer of vanadium in the United States.
The late oxidation that is observed at Gibellini may be unique to shale-hosted vanadium deposits but it’s not unique to the base metal occurrences that form what is known as vanadate deposits. These are typically lead-copper-zinc deposits that have undergone its own supergene enrichment as described above. They occur predominantly in arid climates, most notably in parts of Africa, with Otavi Mountainland in Namibia being the most well-known. The supergene process on these base-metal deposits results in cavities in which vanadate minerals form. Interestingly, the source of vanadium for these deposits has been postulated as coming from nearby shales. That’s right—shale vanadium sources!
Why would all this matter to an investor? In today’s age of information the internet is essentially a modern Library of Alexandria. A wealth of information at your fingertips should you choose to seek it. In the case of vanadium, metallurgy is often front-and-center of the discussion, not only with respect to practicability, but with respect to cost. Knowing the differences between these deposits may offer an investor insight as to the right questions to ask about any project. How the nature of how these deposits occur will affect the mining cost? The permitting? While Aristotle and Plato perhaps were not discussing vanadium on that fresco, they were inquiring as to the nature of things as they are. Above Raphael’s fresco is written in latin Causarum Cognitio, which translates to “knowledge of causes.” As an investor, knowing the causes can perhaps guide your choices by predicting the effects.