460 W. J. MILLER CLASSIFICATION OF METAMORPHIC ROCKS 



i. m eta-igneous 

 Rocks. 



1. Primary or- 

 tho-foliates. 



Secondary or- 

 tho-grneisses 

 and schists. 



1. Gneissoid granite. 



2. Gneissoid syenite. 

 .3. Gneissoid diorite. 



4. Gneissoid gfabbro. 



5. Gneissoid peridotite. 



6. Gneissoid pyroxenite. 



(etcetera.) 



1. Granite-gneiss and schist. 



2. Syenite-gneiss and schist. 



3. Diorite-gneiss and schist. 



4. Gabbro-gneiss and schist- 



5. Peridotite-gneiss and schist. 



6. Pyroxenite-gneiss and schist- 



(etcetera-) 



7. Ortho-amphibolite. 



8. Some ortho-phyllite. 



9. Epidote and chlorite ortho-schists. 



(etcetera.) 



3. Ortho-slate and most ortho-phyllite. 



1. Most serpentine. 



2. Most soapstone. 



3. Apobsidian. 



4. Aporhyolite. 



5. Apotrachyte. 



6. Apoandesite. 



7. Apobasalt- 



(etcetera-) 



[I. MeTA - SEDI 



MENTARY.^ 



Rocks. 



1. Para-gneisses ^ 

 and schists. 



Ill, Injection 



ATES. 



FOLI- 



1. Hornblende-quartz para-gneiss and schist. 



2. Hornblende-biotite para-gneiss and schist. 



3. Pyroxene-quartz para-gneiss and schist. 



4. Quartz-orthoclase para-gneiss and schist. 



5. Quartz-plagioclase para-gneiss and schist. 



6. Hornblende-orthoclase para-gneiss and 



schist. 



7. Quartz-biotite-orthoclase para-gneiss and 



schist, 

 (etcetera-) 

 8 Conglomerate gneiss and schist- 

 9. Impure marble gneiss and schist- 

 ic. Various para-schists— for example, chlorite, 

 glaucophane, and epidote schists. 



11. Para-amphibolite, and eclogite. 



12. Some para-phyllite- 



13. Itabirite and jaspilite. 



(etcetera-) 



IV. Foliates of un- 

 known Origin. 



V. Saprolites. 



2. Para-slate and most para-phyllite. 



1. Quartzite. 



2. Most marble. 



3. Some soapstone. 



4. Some serpentine. 



5. Hornfels- 



6. Anthracite. 



7. Some magnetite- 



8. Various contact metamorphic rocks- 



(etcetera.) 



1. Injected ortho-gneisses and schists. 



2. Injected para-gneisses and schists- 



1. Granitic gneiss and schist. 



2. Syenitic gneiss and schist. 

 3- Dioritic gneiss and schist. 

 4. Gabbroic gneiss and schist. 



5- Peridotitic gneiss and schist. 



6- Pyroxenitic gneiss and schist. 



(etcetera.) 



1. Residual soils and subsoils. 



2. Laterites- 



(etcetera.) 



by chemical alteration under mass-static conditions. Thus most serpen- 

 tines and soapstones are basic igneous rocks in which most of the minerals 

 have altered to serpentine and talc respectively. Here belong also the 



