Source: World wide

Chemical: KAl2(Si3Al)O10(OH,F)2 A rather long equation for a potassium aluminum silicate

Crystal System: Monoclinic

Formation: In igneous rocks and some metamorphic formations.

Properties: Forms mostly in tabular sheets as shown above and below. In large sizes this interesting mineral was once used to make window panes. Large crystal formations will cleave off in perfect sheets, sometimes large enough to make windows. Before there was glass windows there were muscovite windows as shown in the photograph at left. This piece measures over 12 inches by 8 inches as shown beside this US Quarter coin.



Back to Mineral Index Page

Back to Home Page

© Copyright 2011 All Rights Reserved. Please read the fine print below:

The information contained in this website is offered free of charge to anyone wishing to learn more about gemology. The information may be downloaded by any student, consumer, or jeweler for your own personal study and use. None of this site can be downloaded for posting on another website or server for any reason. It will be a violation of the copyright for anyone to copy, duplicate, distribute, and/or re-print this material in any format or any medium without written permission. Nor can anyone post this information on a for-profit website without written permission. That will ruin it for everyone and cause the entire site to be erased and canceled. Please honor this copyright for the good of everyone else.