1. Education
About.com
Geology

Alkali Feldspar Phenocryst in Quartz Monzonite, Cornwall

Phenocryst Gallery

Quartz monzonite contains both major feldspars in roughly equal proportions, plus a little quartz. This is very large for an alkali feldspar crystal.
From a Cornish beach

Alkali feldspar phenocryst in quartz monzonite

Photo provided by a Geology Forum visitor

3 of 10

Gallery Index: Phenocryst Gallery

©2013 About.com. All rights reserved.