Polarized Light Microscopy Digital Image Gallery

Tonalite

Sometimes alternatively referred to as quartz diorite, tonalite is typically comprised of plagioclase feldpar, alkali feldspar, and more than 20 percent quartz. In addition, accessory minerals that are often present in the rock include pyroxenes and amphiboles. Coarse-grained, tonalite is somewhat like granite in appearance, but is often darker in color. Some specimens, however, exhibit what is usually termed "salt and pepper" coloration, consisting of a black and white dappled pattern. A type of tonalite in which biotite is the sole mafic mineral present is sometimes known as trondhjemite. Significant occurrences of tonalite can be found in Alaska, Scotland, Ireland and various other locales around the world.


© 1995-2013 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Thursday, Nov 20, 2003 at 03:51 PM
Access Count Since November 20, 2003: 5448
Microscopes provided by:
Visit the Nikon website. Visit the Olympus Microscopy Resource Center website.