The name given to a fragment of rock with a different origin from the igneous rock in which it is embedded is xenolith.

Here's a breakdown:

* Xeno comes from the Greek word meaning "foreign".

* Lith comes from the Greek word meaning "stone".

So, xenolith literally means "foreign stone".

These fragments are incorporated into the igneous rock during its formation, usually when magma or lava flows through or around pre-existing rocks. They provide valuable insights into the composition and history of the Earth's crust and mantle.