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Rare Earths are not found as free metals in the earth’s crust, but rather within a mixed ‘cocktail’ of Rare Earth elements that need to be separated out into their individual components. To make exploration for rare earth elements profitable, deposits need to be discovered in areas where REEs occur in dense concentration, and there are very few areas in North America where the rare earths are found in abundance.
By Leia Michele Toovey—Exclusive to Rare Earth Investing News
Rare Earths are not found as free metals in the earth’s crust, but rather within a mixed ‘cocktail’ of Rare Earth elements that need to be separated out into their individual components. Despite their name, rare earths are relatively abundant, however, they are often of low quality and rarely presented in economic concentration. The rare earths range in crustal abundance from cerium, the most abundant, at 60 parts per million, which is in fact more abundant than nickel or copper, to thulium and lutetium, the least abundant rare earth elements at about 0.5 parts per million.
There is a significant variance in the prices of selected rare earths oxides (REO). Also, the price of the rare earths depends on the purity level. The principal economic ores of the rare earths are the minerals bastnäsite, loparite, and monazite and the lateritic ion-adsorption clays. Rare earth resources are contained primarily in bastnäsite and monazite. Bastnäsite deposits in China and the United States constitute the largest percentage of the world’s rare-earth economic resources, while monazite deposits in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka, Thailand and the United States constitute the second largest segment. Apatite, cheralite, eudialyte, loparite, phosphorites, rare-earth-bearing (ion adsorption) clays, secondary monazite, spent uranium solutions and xenotime make up most of the remaining resources.
The individual rare earth elements show a great deal of variance when it comes to their presence in the earth’s crust. The rare earths with even atomic numbers are more abundant than their odd number counterparts. Second, the lighter rare earth elements are more incompatible (because they have larger ionic radii) and therefore more strongly concentrated in the continental crust than the heavier rare earth elements. In most rare earth deposits, the first four rare earth elements—La, Ce, Pr, and Nd—constitute 80 percent to 99 percent of the total deposits. Therefore, deposits containing relatively high grades of the scarcer and more valuable heavy rare earth elements, (Gd to Lu, Y and Eu) are particularly valuable.
From the initial discovery of the REE in the late 1700s through the mid-1950s, a few of the REE were produced in modest amounts from monazite-bearing placers and veins, from pegmatite’s and carbonatites, and as minor byproducts of uranium and niobium extraction. During this time, the middle and heavy REE generally were available in pure form only in sub-kilogram quantities and were chiefly chemical curiosities.
To make exploration for rare earth elements profitable, deposits need to be discovered in areas where they occur in dense concentration, and there are very few areas in North America where the rare earths are found in abundance. The number of workable rare earth deposits, already severely limited by the geochemical properties of the rare earths, has in recent years also been affected by environmental and regulatory factors. Monazite, the single most common rare earth mineral, generally contains elevated levels of thorium. Thorium is accompanied by highly radioactive intermediate daughter products, particularly radium, which can accumulate during processing. Concern about radioactivity hazards has now largely eliminated monazite as a significant source of rare earths and focused attention on those few deposits where the REE occur in other, low-Th minerals, particularly bastnäsite.
Approximately 95 percent of the world’s supply of rare earths comes from China. With China using nearly two-thirds of what it produces, it’s naturally keen to protect its own interests. The country is stockpiling its supplies and continuing to reduce annual exports of rare earths. The real concern is that within a few years China may decide to keep everything it produces. As a result, explorations companies around the world are in a race to discover, and develop, the world’s next rare earth mines.
Examples of Rare Earth Deposits
Lynas Corporation’s (AUX:LYC) Mt Weld Rare Earths Oxide (REO) deposit known as the ‘Central Lanthanide Deposit’ (CLD) is without a doubt the world’s richest Rare Earths ore body, capable of supplying up to 20 percent of the global market for 30 years.
Avalon Rare (TSXV:AVL) Avalon’s primary asset is the wholly-owned advanced development stage project, Nechalacho Rare Earth Element Deposit located in the Northwest Territories, Canada. Avalon believes that Nechalacho is one of the highest quality undeveloped REE deposits in the world, unique in its exceptional enrichment in the heavy rare earths. Avalon also owns four other rare metals and minerals project in Canada, of which three are at advanced stages of development.
Rare Element Resources Ltd (TSXV: RES) holds 100% interest in the Bear Lodge property, which contains one of the largest disseminated rare-earth deposits in North America. The Bear Lodge Property contains significant high-grade rare earth elements in carbonatite dikes. An updated NI 43-101-compliant inferred mineral resource estimate reports two REE deposits containing 17.5 million tons averaging 3.46% rare-earth oxides at 1.5% REO cutoff grade, and at 4% REO cutoff grade the deposits contain 4.4 million tons averaging 6.65% REO. The oxide mineralization consists of 8.0 million tons averaging 3.62%, including 2.3 million tons averaging 6.90% REO. Exploration potential continues to be excellent; the two rare-earth deposits are open in several directions and other targets remain to be tested.