Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Spontaneously igniting in air.
  • adjective Producing sparks by friction.

from The Century Dictionary.

  • Same as pyrophorous.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Light-producing; of or pertaining to pyrophorus.
  • adjective (Chem.) finely reduced iron, which ignites spontaneously on contact with air.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective spontaneously igniting in air, especially when in a finely divided state
  • adjective producing sparks, especially by friction
  • adjective Able to oxidize with exposure to atmospheric oxygen at normal temperatures.

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[From pyrophorus, substance that ignites spontaneously : from Greek purophoros, fire-bearing : puro-, pyro- + -phoros, -phorous.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek πυροφόρος ("fire-bearing") +‎ -ic.

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Examples

  • The company got a chance to show that when a customer had an accidental release of a "pyrophoric" gas that can ignite on contact with air.

    China Slowdown Stunts Entrepreneurs 2009

  • Depleted uranium is "pyrophoric", which makes it uniquely effective at piercing hard targets, because upon impact, it immediately burns, vaporizing the majority of its bulk and leaving a hard, thin, sharpened tip - and large amounts of radioactive particles suspended in the atmosphere.

    Honor Vets by Learning About Depleted Uranium 2008

  • Finely divided uranium powder is pyrophoric, meaning it will ignite spontaneously at room temperature.

    About.com Chemistry 2010

  • Uranium in its pure form is a silver-colored heavy metal that is nearly twice as dense as lead and is pyrophoric when finely divided.

    Uranium 2009

  • Finely divided uranium metal, being pyrophoric, presents a fire hazard.

    Uranium 2009

  • Raney-Ni is known to be a very active catalyst for hydrogenation and a pyrophoric material, indeed a dangerous one to be handled with care that has on occasion exploded.

    Rabett Run EliRabett 2008

  • It turns out the uranium from nuclear waste is very dense and possesses pyrophoric properties.

    BLOW-HARDS News from Mad Plato 2008

  • It turns out the uranium from nuclear waste is very dense and possesses pyrophoric properties.

    Archive 2008-03-01 News from Mad Plato 2008

  • A bit more about DU – When fired or exploded, it is pyrophoric, becoming a tremendous fiery explosion, and reaches high temperatures between 3,000-6,000 degrees Centigrade.

    No More DU, No More Hiroshimas, No More Nagasakis 2008

  • Due to the pyrophoric nature of uranium metal and the extreme temperatures generated on impact of depleted uranium ammunition on a hard target, it ignites and produces an aerosol of fine particles of uranium oxides if the temperature exceeds 600°C.

    Depleted uranium 2008

Comments

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  • So is this another way to describe spontanious combustion?

    September 27, 2010

  • I would say yes - spontaneous combustion under certain conditions.

    December 20, 2022