Contains

• 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...

• basalt

  The commonest type of solidified lava; a dense dark grey fine-grained igneous rock that is...

• dacite

  A grey volcanic rock containing plagioclase and quartz and other crystalline minerals.

• agglomerate

  Volcanic rock consisting of large fragments fused together.

• amygdaloid

  Volcanic rock in which rounded cavities formed by expanding gas have subsequently become...

• tuff

  Hard volcanic rock composed of compacted volcanic ash.