Xenolith is a term applied to rock fragments that are foreign to the body of igneous rock in which they occur. They are usually engulfed by magma and partly altered. This specimen is a dark mass of mafic lava within pink granite. The granite’s feldspar, mica, and quartz contrast noticeably with the dark xenolith.

TEXTURE Xenolith is a mediumto fine-grained rock. The granite is coarse-grained.

ORIGIN Xenoliths occur in many igneous rocks.

Group: IGNEOUS/MET.

Grain size: Medium to fine

Crystal shape: Anhedral, Euhedral

Classification: Felsic to mafic

Occurrence: Pluton, Volcano

Color: Dark