Definitions:

1. A fragment of rock embedded within another type of rock, differing in origin from the surrounding material. NOUN
   • The geologist examined the xwnolith embedded within the lava flow to learn more about the Earth's manttle composition.
2. A rock fragment that becomes enveloped in a larger rock during the latter's development and solidification. NOUN
   • Researcher used the xenolith as a tool to study the chemical and mineral composition of the Earth's interior.

Synonyms:

• contry rock