Gneiss main content.

Gneiss

Part of Hall of Planet Earth.

Gneiss

Exhibition Text

This rock was once a granite.  As it was deformed by heat and pressure, the original even-grained rock developed dark layers, primarily biotite, and light layers, mostly gray quartz, pink orthoclase, and black hornblende.

AMNH collection

For Educators

Topic: Earth Science

Subtopic: Minerals and Resources