CLASSIFICATION OF IGNEOUS ROCKS 57 



though when it is present the rock may be classed as a sub- 

 family, comparable to one in the normal granite family, namely 

 as Muscovite-granite-greisen. 



(123) Adamellite-greisen. The rock for which the term 

 adamelHte-greisen is here proposed is related to the quartz- 

 monzonites (adamellites) as granite-greisen is to normal granite. 

 For the use of the term adamellite for quartz-monzonite see note 

 under (228). 



(124) Granodiorite-greisen. See note under (123). 



(125) Tonalite-greisen. See note under (123). 



(127) Leucogranite differs from normal granite (227) in the 

 practical absence of mafic minerals. It therefore consists of quartz, 

 orthoclase, and a less amount of oligoclase or andesine. 



Leucorhyolite. The extrusive equivalent of the preceding. 



(128) Leucoadamellite. See note under (127). 

 Leucodellenite. The extrusive equivalent of the pre- 

 ceding. 



(129) Leucogranodiorite. See note under (127). 

 Leucorhyodacite. The extrusive equivalent of preced- 

 ing. See note under rhyodacite (229). 



(12 10) Leucotonalite. See note under (127) for the relation- 

 ship between this rock and normal tonalite. For the use of tonalite 

 for quartz-diorite see (2210). According to the kind of feldspar 

 present, the leucotonalites are divided into quartz-oligosites Turner 

 (quartz-oligoclasites) , and quartz-andesinites Turner. See note 

 under (121 5). 



Quartz-oligosite Turner. 



Quartz-andesinite Turner. 



Leucodacite. The extrusive equivalent of leucotonalite. 



(121 2) Leucosyenite. See note under (127). 

 Leucotrachyte. The extrusive equivalent of preceding. 



(1213) Leucomonzonite. See note under (127). 

 Leucolatite. The extrusive equivalent of preceding. 



(12 14) Leucomonzodiorite. In the former paper the writer^ 

 suggested the term syenodiorite, from analogy with granodiorite, 



'Albert Johannsen, "Suggestions for a Quantitative Mineralogical Classification 

 of Igneous Rocks," Jour. GeoL, XXV (1917), 89. 



