from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A granitic rock composed chiefly of quartz and mica.
from The Century Dictionary.
- noun A rock of the granitic family, having a crystalline-granular texture, and chiefly made up of quartz and mica.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Min.) A crystalline rock consisting of quarts and mica, common in the tin regions of Cornwall and Saxony.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun geology A highly altered
granitic rockcontaining quartzand mica
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun a granitic rock composed of quartz and mica
from The American Heritage® Dictionary of the English Language, 4th Edition
[German, from greissen, to split.]
The wall rocks are usually strongly altered and in part are replaced by some of the above minerals, forming coarse-grained rocks which are called "greisen."