UNIVERSITY OF CALIFORNIA 



Bulletin of the Department of Geology 



Vol. I, No 12, pp. 337-362, PI. IH. ANDREW C. LAWSON, Editor 



ON 



M A L I G N ITE, 



A FAMILY OF BASIC PLUTONIC ORTHOCLASE ROCKS 

 RICH IN ALKALIES AND LIME 



INTRUSIVE IN THE COUPCHICHING SCHISTS OF POOH- 

 BAH LAKE. 



BY 



Andrew C. Lawson. 

 CONTENTS. 



Page. 



Introduction.. 337 



Nepheline-Pyroxene-Malignite 342 



Macroscopic Characters 342 



Structure , 343 



Mineralogica) Details 344 



Chemical Characters 349 



Petrographic Relations 351 



Panidiomorphic Gneissic Facies 352 



Garnet-Pyroxene-Malignite 353 



General Features 353 



Microscopic Characters 354 



Chemical Analysis 356 



Minor Facies 357 



Amphibole-Malignite 357 



Mineralogical Composition 357 



Chemical Analysis 35S 



Concluding Remarks 359 



INTRODUCTION. 



Pooh bah Lake lies in the District of Rainy River, in the Prov- 

 ince of Ontario, Canada. The detail of its geographic relations may- 

 be ascertained by an inspection of the Hunters Island sheet of the 



