XVII 



CLASSIFICATION OF VOLCANIC ROCKS 



2 39 



SYNOPSIS 

 I. CLASS. OLIVINE ROCKS (Flag., oliv.}. 



SUB-CLASS. 



DIVISION. 



ORDER. 1 



No groundmass 

 (non-matr.} 



LlMBURGITES, 



PERIDOTITES, 



OLIVINE GABBROS, 



etc. 



Groundmass (matr.} 

 OLIVINE-BASALTS. 



Olivine abundant 

 (cop.) 



Olivine relatively 

 scanty (pauc.}. 



(Not represented in collection.) 



Felspar lathes not in flow-arrange- 

 ment (non-flu.}. 



2. 



Felspar lathes in flow-arrange- 

 ment (flu.}. 



3- 



Felspar lathes not in flow-arrange- 

 ment (non-flu. }. 



Felspar lathes in flow-arrange- 

 ment (flu. }. 



1 Each division would theoretically also possess an orthophyric and a felsitic 

 order ; but these orders are not represented in my collection and need only be 

 mentioned. 



II. CLASS. AUGITE ROCKS (Flag., aug.\ 



SUB-CLASS. 



ORDER. 



No groundmass (non-matr. } 

 GABBROS, in part. 



Groundmass (matr.} 



BASALTIC ANDESITES ; 



AUGITE-ANDESITES ; 



PYROXENE-ANDESITES 



in part. 



Not represented in collection. 



Felspar lathes not in flow-arrangement (non-flu. }. 



Felspar lathes in flow-arrangement (flu. }. 



Felspars short and broad (orthophyric, orth.}.- 



k Groundmass felsitic 



1 Not represented in the collection. 



