1915. 



NATURAL SCIENCES OF PHILADELPHIA. 



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Oxides; double; rare-earth-: ilmenite, pseudobrookite 



Sulfides; nonmetallic: molybdenite 



metallic : pyrite ; chalcopyrite 



Elements; nonmetallic: graphite 



metallic : gold 



b. Metamorphosed (additional to those of a, which may be recrystal- 

 lized by metamorphism) 



Orthosilicates; epidotes: zoisite, piedmontite 



I. 1. B. Alkalic Igneous Rocks 



a. Primary 



Silicon oxides: 

 Feldspars; orthoclases: 



plagioclases: 

 Metasilicates; leucites: 



pyroxenes : 

 amphiboles : 



rare-earth-: 

 Orthosilicates; garnets: 



nephelites : 

 sodalites : 

 melilites : 

 micas : 

 rare-earth- : 



(quartz) 



orthoclase, anorthoclase, micro- 



cline 

 albite, oligoclase, andesine 

 leucite 



acmite, segirite 

 hornblende, arfvedsonite, barke- 



vikite, riebeckite, enigmatite 

 lovenite 

 andradite 



nephelite, cancrinite 

 sodalite, hauynite, noseUte 

 melilite 

 biotite 

 zircon 



