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Which would most likely cause molted rock material to became glassy igneous rock?

1.- cooling over a long period of the time

2.- coolng under high pressure

3.- cooling on Earth's surface

4.- cooling at great deapth within the crust

2 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    (3) Cooling at the surface and doing it VERY rapidly. That's how you get obsidian.

    Source(s): Geologist
  • Anonymous
    1 decade ago

    3-Cooling on Earth's surface

    Glass is formed by extremely rapid cooling of magma, rates that are nearly exclusive to lavas on the surface of the Earth.

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