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  1. How rare exactly are 'rare earth elements'? I'll use IUPAC's definition.

A rare-earth element (REE) [...] as defined by the International Union of Pure and Applied Chemistry, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium.

  1. Does China uniquely possess some 'rare earth elements' that haven't been discovered elsewhere? Which?

Some Reddit comments avouch rare earth metals aren't rare, substantiated by 16 million tons of rare metals found under the Pacific Japan near Japan in Apr 2018.

Researchers have found hundreds of years’ worth of critical rare-earth metals beneath Japanese waters — enough to supply to the world on a “semi-infinite basis,” according to a study published on Tuesday.

The materials sit in a roughly 965-square-mile Pacific Ocean seabed near Minamitorishima Island, which is located 1,150 miles southeast of Tokyo, according to the study published in Nature Publishing Group’s Scientific Reports.

Rare-earth metals are crucial in the making of high-tech products such as electric vehicles, mobile phones and batteries, and the world has relied on China for almost all of its rare-earth material.

The seabed contains more than 16 million tons of rare-earth oxides, according to the study. That’s equivalent to 780 years’ worth of yttrium supply, 620 years of europium, 420 years of terbium and 730 years of dysprosium, it added.

The discovery “has the potential to supply these metals on a semi-infinite basis to the world,” the study said.

But "Semi-infinite" is an awful term.

Semi-infinite doesn't say anything about the density, depth, size or difficulty to extract the minerals. The Earth contains a semi-infinite amount of Platinum too. But nobody says things like that.

Pentagon legislation seeks to end US dependence on Chinese rare earth metals : wallstreetbets

REMs actually aren't that rare, despite their name. Japan recently found deposits that could basically supply Earth from now to infinity. The US has huge deposits as well.

China accounts for around 80% of U.S. rare earths supply. : wallstreetbets

Rare earth minerals aren't rare at all, they're all over the world, including the US and Canada. Many of the mines in the developed world were shut down because they're kind of an environmental nightmare war zone. Environmental regulations in the developed world make them more expensive to mine here, but China don't give a fuck. Check out this BBC report of giant toxic lakes in Mongolia.

Pentagon in talks with Australia on rare earths plant : geopolitics

There's two big misconceptions about rare-earth minerals and neither are true.

The first is that they're mostly found in China. Actually, there's significant deposits on every continent, and abundant stocks in sea floor muds. The second is that they're rare. Developing them can be costly and if we want more than one source, we're going to need to come up with some new processes, but it is and always has been a matter of impetus for making the investment, never a case that one world power would have the ability to choke off the supply to worldwide industry.

But other Reddit comments avouch that "you can only find heavy rare earth materials in China.

Urthor comments on Pentagon in talks with Australia on rare earths plant.

There is a large subsection of rare earth materials that are not found outside of China in any mining development.

There's I believe a list of 18 and Australia's Lynas only has about 5-6 iirc, and altogether the world can't cobble all 18 together without relying on China.

To get the entire Pokedex of materials would involve major greenfields mining operations. Plus rare earths are honestly not the most profitable enterprise in the first place, Lynas by and large survives due to very favourable Japanese loans and the incredibly unusual step of being acquired by Australia's Walmart equivalent in a deal that reeks of political involvment.

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  • @Bitterdreggs I edited my post to clarify. Better?
    – NNOX Apps
    May 30 '20 at 3:42
  • Better, yes. I'm not sure how it will go down having a redit post as notable source though, especially since the comment 2 from the top claims to contradict it with this link to a study (mind you it lacks certain details). I leave it to others to figure out. May 30 '20 at 4:19
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    I am still trying to work out what the second claim is. Some were discovered in mines in Scandinavia. There are deposits of rare earths under Japan. There is a mine in Australia. One random redditor says the Australian mine doesn't have many different elements. Someone else gives a reference showing REE are mined around the world. Do we have a clear notable claim?
    – Oddthinking
    May 30 '20 at 5:26
  • Don't get hung up on what people call things. As you can see, the definition has nothing to do with how rare they are. This question is easily answered, they are actually rarer than most and quite difficult to distinguish, but they are grouped together because of their chemistry and number of protons and not by their abundance. Most would mention f-orbitals here, so will i. They form a set of quite similar elements, some of which might not be as rare. But don't get hung up on names so much and spent more effort reading your own definition.
    – Raditz_35
    May 30 '20 at 9:21
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    There is no notable claim here since nobody seems to be claiming they are rare. The name is a historical accident not a claim.
    – matt_black
    May 30 '20 at 15:30
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This is trivially answered by Wikipedia:

Despite their name, rare-earth elements are – with the exception of the radioactive promethium – relatively plentiful in Earth's crust, with cerium being the 25th most abundant element at 68 parts per million, more abundant than copper.

This is backed up by the book Patty's Toxicology. The chapter titled The Lanthanides, Rare Earth Elements explains they are common, and gives some of the etymology that causes such confusion:

The elements scandium and yttrium are also known as the “rare earths” because they were originally discovered together with the lanthanides in rare minerals and isolated as oxides, or “earths.” Collectively, these metals are also called rare earth elements (REEs). In comparison with many other elements, however, the rare earths are not really rare, except for promethium, which has only radioactive isotopes. Yttrium, lanthanum, cerium, and neodymium are all more abundant than lead in the earth's crust. All except promethium, which probably does not occur in nature, are more abundant than cadmium.

Promethium is the one exception: it's most stable isotope has a half-life of only 17.7 years, which means

it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time

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  • Thanks. Does your answer address my question 2?
    – NNOX Apps
    May 30 '20 at 5:19
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    Your question #2 needs work.
    – Oddthinking
    May 30 '20 at 5:20
  • What "work"? I revised this question's title.
    – NNOX Apps
    May 30 '20 at 19:54
  • See my comments on the main question, which your edit doesn't help.
    – Oddthinking
    May 31 '20 at 5:37

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