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  2. 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.

  3. Nines (notation) - Wikipedia

    en.wikipedia.org/wiki/Nines_(notation)

    For example, a N2.0 gas is 99% (two nines) pure and 1% impurities by volume; a N6.0 gas is 99.9999% (six nines) pure, with 1 part per million (1 ppm or 1 vpm, volume per million) impurities. [7] Intermediate values indicate the digit following the last nine. For example, N4.6 estimates a purity level of 99.996% (four nines followed by a six). [7]

  4. 999 - Wikipedia

    en.wikipedia.org/wiki/999

    Nine (purity), an informal way of ranking purity; "three nines" would be 99.9% pure "Three nines" as a level of high availability (99.9%) Triple Nine Society, a society for people with IQs in the 99.9th percentile

  5. Fineness - Wikipedia

    en.wikipedia.org/wiki/Fineness

    For example, knowing that standard 18-karat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by mass), the volume of pure gold in this alloy will be 60% since gold is much denser than the other metals used: 19.32 g/cm 3 for gold, 10.49 g/cm 3 for silver and 8.96 g/cm 3 for copper.

  6. Oxygen-free copper - Wikipedia

    en.wikipedia.org/wiki/Oxygen-free_copper

    This is a 99.99% pure copper with 0.0005% oxygen content. It achieves a minimum 101% IACS conductivity rating. This copper is finished to a final form in a carefully regulated, oxygen-free environment. Silver (Ag) is considered an impurity in the OFE chemical specification. This is also the most expensive of the three grades listed here.

  7. Silver standards - Wikipedia

    en.wikipedia.org/wiki/Silver_standards

    Ninety-one (91) zolotniks have the equivalent millesimal fineness of 947[9]. Thus, the alloy contains 94.79% pure silver and 5.21% copper or other metals. [4] [5] Sterling silver has a millesimal fineness of 925. The sterling silver alloy is 92.5% pure silver and 7.5% copper or other metals.

  8. Sterling silver - Wikipedia

    en.wikipedia.org/wiki/Sterling_silver

    Fine silver, which is 99.9% pure silver, is relatively soft, so silver is usually alloyed with copper to increase its hardness and strength.Sterling silver is prone to tarnishing, [1] and elements other than copper can be used in alloys to reduce tarnishing, as well as casting porosity and firescale.

  9. 68–95–99.7 rule - Wikipedia

    en.wikipedia.org/wiki/68–95–99.7_rule

    For an approximately normal data set, the values within one standard deviation of the mean account for about 68% of the set; while within two standard deviations account for about 95%; and within three standard deviations account for about 99.7%.