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  2. Fraunhofer lines - Wikipedia

    en.wikipedia.org/wiki/Fraunhofer_lines

    There is disagreement in the literature for some line designations; for example, the Fraunhofer d line may refer to the cyan iron line at 466.814 nm, or alternatively to the yellow helium line (also labeled D 3) at 587.5618 nm. Similarly, there is ambiguity regarding the e line, since it can refer to the spectral lines of both iron (Fe) and ...

  3. Metallicity - Wikipedia

    en.wikipedia.org/wiki/Metallicity

    The globular cluster M80. Stars in globular clusters are mainly older metal-poor members of population II. In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non- dark) matter in the universe is either hydrogen or helium, and ...

  4. Helium - Wikipedia

    en.wikipedia.org/wiki/Helium

    Helium. hexagonal close-packed (hcp) Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.

  5. Helium storage and conservation - Wikipedia

    en.wikipedia.org/wiki/Helium_storage_and...

    Helium storage and conservation is a process of maintaining supplies of helium and preventing wasteful loss. Helium is commercially produced as a byproduct of natural gas extraction. Until the mid-1990s, the United States Bureau of Mines operated a large scale helium storage facility to support government requirements for helium.

  6. The U.S. just sold its helium stockpile. Here's why the ...

    www.aol.com/news/u-just-sold-helium-stockpile...

    On Thursday, the U.S. government sold the Federal Helium Reserve, a massive underground stockpile based in Amarillo, Texas, that supplies up to 30% of the country’s helium.

  7. The Helium Cliff: Will Government Gridlock Send Prices ... - AOL

    www.aol.com/.../helium-cliff-soaring-prices-congress

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  8. Prices of chemical elements - Wikipedia

    en.wikipedia.org/wiki/Prices_of_chemical_elements

    In the form of boric acid, price per boron contained. Min. 99% pure. 6: C: Carbon: 2.267: 200 (5.54 × 10 18 kg) 0.122: 0.28: 2018: EIA Coal [19] In the form of anthracite, price per carbon contained, assuming 90% carbon content. There is a wide variation of price of carbon depending on its form.

  9. Metal prices - Wikipedia

    en.wikipedia.org/wiki/Metal_prices

    Metal prices. Metal prices are the prices of metal as a commodity that are traded in bulk at a predefined purity or grade. Metal can be split into three major categories, precious metals, industrial metals and other metals. Precious metals and industrial metals are priced by trading of those metals on commodities exchanges. [1]