paragonite

from The Century Dictionary.

• noun A kind of mica, analogous to muscovite in composition, but containing sodium in place of potassium: it is characteristic of the paragonite-schist of the Alps.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) A kind of mica related to muscovite, but containing soda instead of potash. It is characteristic of the paragonite schist of the Alps.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mineralogy A mineral related to muscovite.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a colorless or pale brown mica with sodium