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The cerium anomaly, in geochemistry, is the phenomenon whereby cerium (Ce) concentration is either depleted or enriched in a rock relative to the other rare-earth elements (REEs). [1] A Ce anomaly is said to be "negative" if Ce is depleted relative to the other REEs and is said to be "positive" if Ce is enriched relative to the other REEs. [1]
Some of the bastnäsites contain OH − instead of F − and receive the name of hydroxylbastnasite. Most bastnäsite is bastnäsite-(Ce), and cerium is by far the most common of the rare earths in this class of minerals. Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare-earth elements.
Cerium is the most abundant of all the lanthanides and the 25th most abundant element, making up 68 ppm of the Earth's crust. [45] This value is the same of copper, and cerium is even more abundant than common metals such as lead (13 ppm) and tin (2.1 ppm).
The rare earth element neodymium is found in monazite, making it a rare mineral. [25] Moreover, monazite contains many other rare metals such as cerium, lanthanum, praseodymium, and samarium, making it a critical source of renewable energy. [26] Recycled magnets can also be derived from these minerals due to the metals they contain. [25]
The USGS study team has located a sizable area of rocks in the center of an extinct volcano containing light rare-earth elements including cerium and neodymium. It has mapped 1.3 million metric tons of desirable rock, or about ten years of supply at current demand levels. The Pentagon has estimated its value at about $7.4 billion. [185]
Samarium is not absorbed by plants to a measurable concentration and so is normally not part of human diet. However, a few plants and vegetables may contain up to 1 part per million of samarium. Insoluble salts of samarium are non-toxic and the soluble ones are only slightly toxic.
New tests done by the Environmental Working Group have found 21 oat-based cereals and snack bars popular amongst children to have "troubling levels of glyphosate." The chemical, which is the ...
Naturally occurring cerium (58 Ce) is composed of 4 stable isotopes: 136 Ce, 138 Ce, 140 Ce, and 142 Ce, with 140 Ce being the most abundant (88.48% natural abundance) and the only one theoretically stable; 136 Ce, 138 Ce, and 142 Ce are predicted to undergo double beta decay but this process has never been observed.