Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Photomicrography
Microscopy Museum
Virtual Microscopy
Fluorescence
Web Resources
License Info
Image Use
Custom Photos
Partners
Site Info
Contact Us
Publications
Home

The Galleries:

Photo Gallery
Silicon Zoo
Pharmaceuticals
Chip Shots
Phytochemicals
DNA Gallery
Microscapes
Vitamins
Amino Acids
Birthstones
Religion Collection
Pesticides
BeerShots
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Polarized Light Microscopy Digital Image Gallery

Mylonite

The term mylonite was first utilized in 1885 by Charles Lapworth to describe a fine-grained, laminated rock that he discovered in the Moine Thrust Zone of Scotland. Since that time, the word has become a general structural indicator of any distinctly foliated, fine-grained rock associated with a high level of ductile deformation.

View a second image of Mylonite

Mylonites, which can be found among rocks of all ages, are typically believed to be only formed in shear zones. Pressure, temperature, and strain are the primary factors that determine whether or not a mylonite or some other type of metamorphic rock will form when intense folding or faulting occurs. If these dynamics fall outside of a certain range, the process of metamorphism may result, for instance, in a cataclastite, gneiss, or granulite, rather than a fine-grained, highly laminated mylonite. In addition, mylonites require two discrete kinds of constituents in order to form: a hard element that generates larger-grained porphyroclasts and a softer element, which develops into the rock’s fine-grained matrix.

Zones of mylonite occur around the world and vary greatly in size. In Nevada, deposits of mylonite have been found that are not more than a centimeter thick, while in Canada, a mylonite zone exists that is several kilometers thick and several hundred kilometers long. No matter their size, deposits of mylonite can reveal important clues regarding the geological history of the region in which they are found. The rocks are, for example, clear indicators of the presence of a shear zone that was previously active, and close examination of samples may bring to light details concerning the type and extent of shearing that transpired.


BACK TO THE ROCKS AND MINERALS GALLERY

BACK TO THE POLARIZED LIGHT GALLERY

Questions or comments? Send us an email.
© 1998-2013 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, 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: Tuesday, Jul 25, 2006 at 10:34 AM
Access Count Since November 20, 2003: 9722
For more information on microscope manufacturers,
use the buttons below to navigate to their websites: