Wikipedia is best for references, not its original writing.
Compare these two paragraphs:
Promethium is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500-600 grams naturally occurring in Earth’s crust at any given time.
Los Alamos National Laboratories:
Searches for the element on earth have been fruitless, and it now appears that promethium is completely missing from the earth’s crust. Promethium, however, has been identified in the spectrum of the star HR465 in Andromeda. This element is being formed recently near the star’s surface, for no known isotope of promethium has a half-life longer than 17.7 years.
Wikipedia wasn’t dependable when it began but it is much better now. It has to be checked, though, like all research sources. Today, I see magazine articles written solely from online materials. This is disastrous. You need information from online resources, research from authoritative books and magazines, and personally gathered quotes from experts.
Anything else is lazy.
Another research problem. Promethium’s density is likely undetermined, despite what this graphic and most sources state. I do not have enough certainty of that, however, to commit to this in print. When in doubt, say matters remain unsettled. A writer is not required to answer all questions.
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