Gneiss main content.


Part of Hall of Planet Earth.


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

Keywords: Gneiss, Geology, Minerals, Granite

Audience: General