T. S. Hunt on Lithology. ae. 259 
gradations from albite to anorthite that the various intermediate 
species which have been distinguished seem to pass into each 
other. (This Journal, [2], xviii, 270. Phil. Mag. [4], ix, 262.) 
Next to the feldspars in lithological importance are the two 
species, pyroxene and hornblende. These are sometimes found 
drated micas observed by Haughton in many of the Irish gran- 
trivial names which have been from time to time imposed. In 
the case of simple rocks the terms quartzite, pyroxenite, anortho- 
site, and orthoclasite are sufficiently definite, or they may be fur- 
micaceous, and quartzo-micaceo-hornblendic orthoclasite would 
clase and black mi 
albite, and quartz. Pete? 
The structure of these orthosite rocks gives rise also to a great 
ty of names; thus to coarsely lamellar granites the name 
of pegmatite is sometimes given, while fine grained mixtures of 
