volcanic rock

Noun
  1. Extrusive igneous rock solidified near or on the surface of the Earth (synset 114957452)
    is a type of: igneous rock - rock formed by the solidification of molten magma
    subtypes:
    • agglomerate - volcanic rock consisting of large fragments fused together
    • amygdaloid - volcanic rock in which rounded cavities formed by expanding gas have subsequently become filled with mineral deposits
    • dacite - a grey volcanic rock containing plagioclase and quartz and other crystalline minerals
    • basalt - the commonest type of solidified lava; a dense dark grey fine-grained igneous rock that is composed chiefly of plagioclase feldspar and pyroxene
    • volcanic glass - a kind of natural glass produced when molten lava cools very rapidly
    • lava - rock that in its molten form (as magma) issues from volcanos; lava is what magma is called when it reaches the surface
    • tufa, tuff - hard volcanic rock composed of compacted volcanic ash

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