• A rock fragment foreign to the igneous mass in which it occurs.
  • In <em>petrography</em>, a term proposed by Sollas (1894) for a rock inclosed in an intrusive rock, and not derived from the igneous magma.
  • any piece of <xref>rock</xref> having a different <xref>origin</xref> to that of the <xref>igneous</xref> rock in which it is found
  • (geology) a piece of rock of different origin from the igneous rock in which it is embedded
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