Sand-sized particles of igneous rock that form when a spray of liquid magma is blown from a volcanic vent by escaping gas. Fine pyroclastic material; particle diameter is less than 4 millimeters.
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Sand-sized particles of igneous rock that form when a spray of liquid magma is blown from a volcanic vent by escaping gas. Fine pyroclastic material; particle diameter is less than 4 millimeters.
Related terms: