By Steve Voynick
Of the roughly 155 vanadium-bearing minerals, many of them brightly colored, collectors are probably most familiar with vanadinite, mottramite, and cavansite.
With its hexagonal, orange-red prisms, vanadinite, or lead chlorovanadate, is the most collectible. Mottramite, basic lead copper vanadate, is collected for its greenish-yellow encrustations and botryoidal structures, and cavansite, hydrous calcium vanadium oxysilicate, for its vivid-blue, spherical aggregates.
Because of a mutual chemical affinity, about a third of all vanadium-bearing minerals contain uranium. These include carnotite, a hydrous potassium uranium vanadate, and tyuyamunite, a hydrous calcium uranium vanadate, both of which occur as bright, canary-yellow encrustations.
Elemental vanadium is not as showy as many of its minerals. It is a silvery-white metal as dense as iron, but with a substantially higher melting point. Ranking 19th in crustal abundance, it is about as common as chromium and nickel.
Although relatively ductile and malleable, it is one of the hardest of all metals at Mohs 7.0. Because of its affinity for oxygen, elemental vanadium is rare in nature and has been found only as a sublimate in the cone of Mexico’s Colima Volcano.
In 1801, Spanish mineralogist Andrés Manuel del Río proposed the existence of a previously undiscovered metal in a mixture of lead minerals, an observation confirmed in 1830 by German mineralogist Friedrich Karl Wöhler. The following year, Swedish chemist Nils Gabriel Sefström, experimenting with iron ores, extracted a colorful oxide of this mysterious metal from which he produced other brightly colored compounds. Sefström named this still-unseen metal “vanadium,” after Vanadis, one of the names of the Norse goddess of beauty, alluding to its colorful compounds.
Vanadium Changes Market Interest
Elemental vanadium was finally isolated in 1867 as a laboratory curiosity obtainable only in small quantities from vanadinite and as a by-product of iron smelting. In 1890, French metallurgists discovered that small amounts of vanadium enhanced the hardness, tensile strength, toughness, and corrosion-resistance of steel. Steelmakers, however, were hesitant to adopt vanadium-steel alloys. As demand slowly grew, a Peruvian deposit of patrónite (vanadium sulfide) became the first commercial source of vanadium in 1901.
Industry-wide acceptance of vanadium-steel alloys came about through the work of the pioneering American automobile manufacturer Henry Ford. While seeking materials for his Model T automobiles in 1910, Ford inspected a European racing car that had crashed at the new Indianapolis Motor Speedway. The impact had bent or fractured all its chassis and power-train components—except for the crankshaft, which consisted of a new vanadium-steel alloy.
The vanadium in those Model Ts came from Colorado carnotite ore and mill tailings, which had originally been mined for their tiny radium content. Patrónite and carnotite are the only minerals ever mined as primary ores of vanadium.
Today, vanadium is obtained as a by-product of processing vanadiferous iron and titanium ores, iron slags, and petroleum residues. Of the 80,000 tons of vanadium recovered worldwide each year, 95 percent is alloyed with steel. In ready-to-alloy, elemental form, vanadium sells for about $10 per pound.
Vanadium In Industry
Vanadium-steel alloys are used in pipeline sections, high-speed tool steels, and structural-steel girders. Vanadium-chrome steels are standard in automotive suspension springs, transmission gears, and high-stress engine components, while lightweight, heat-resistant, vanadium-aluminum-titanium alloys are vital in heat-resistant components of jet and rocket engines.
Knowing a bit about vanadium’s history and uses makes those colorful specimens of vanadinite, mottramite, and cavansite all the more interesting.
Author: Steve Voynick
A science writer, mineral collector, and former hard rock miner, he is also the author of many references including, “Colorado Rock Hounding” and “New Mexico Rockhounding.”