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Gneiss

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

Keywords: Gneiss, Geology, Minerals, Granite

Audience: General