Definitions

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

  • adjective Composed chiefly of rock fragments or particles of volcanic origin, such as pumice, obsidian, or volcanic ash.

from The Century Dictionary.

  • Formed by volcanic agencies, or in the process of being erupted: applied to volcanic breccia or to any angular or comminuted material of igneous origin.
  • noun A pyroclastic rock.

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

  • adjective volcanology Mostly composed of rock fragments of volcanic origin
  • noun A rock mostly composed of rock fragments of volcanic origin

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

From pyro- +‎ clastic, from Ancient Greek πῦρ (pur, "fire"), and κλαστός (klastos, "broken").

Examples

  • The heavier particles stay close to the ground and roll downhill in what we call a pyroclastic flow.

    Asimov's Science Fiction

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    Scientists find it difficult to predict volcano behavior

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    Scientists find it difficult to predict volcano behavior

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    Scientists find it difficult to predict volcano behavior

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    Scientists find it difficult to predict volcano behavior

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    Scientists find it difficult to predict volcano behavior

  • At least 90 people were killed as a superheated clouds of ash, gas and debris known as pyroclastic flows tumbled down the mountain and incinerated villages.

    Some Flights Resume Following Indonesia Volcano

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    digg.com: Stories / Popular

  • Hundreds of thousands of people live beneath it and could be hit with what are known as pyroclastic flows -- extremely fast-moving, dense clouds of hot ash and rock that flow down the mountain.

    digg.com: Stories / Popular

  • Red-hot clouds of gas and fine ash known as pyroclastic density currents flowed down the slopes of Vesuvius, engulfing Pompeii's frescoed villas, as well as its shops, public baths and brothels, where explicit erotic paintings and the customers' graffiti can still be seen.

    canada.com Top Stories

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