• Guessologist@lemmy.world
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    1 year ago

    It’s all about how much silica is in the lava - not much and you have basalt, fairly runny so the gas escapes and you get fire fountaining and lava flows. More silica gives you very viscous lava like rhyolite or andesite - traps the gases, far more explosive and dangerous eruption styles.

    • A_A@lemmy.world
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      1 year ago

      You are right
      …and my use of “plutonic” is either outdated or plainly wrong.
      I found this for anyone who wants to read more :
      https://en.m.wikipedia.org/wiki/Lava
      Properties of lava

      Because of the role of silica in determining viscosity and because many other properties of a lava (such as its temperature) are observed to correlate with silica content, silicate lavas are divided into four chemical types based on silica content:
      felsic,
      intermediate,
      mafic, and
      ultramafic.