Vol. 5, No. 23, pp. 331-380, Pis. 27-39' ANDREW C. LAWSON, Editor 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



BENITOITE, ITS PARAGENESIS AND 

 MODE OF OCCURRENCE. 



BY 



GEORGE DAVIS LOUDERBACK. 



with Chemical Analyses by 

 WALTER C. BLASDALE. 



CONTENTS. 



PAGE 



Introduction 332 



The Locality _ 333 



General Geological Surroundings 334 



Occurrence 336 



Effects of Earth Movement and Pressure 337 



Size and Attitude of Outcrop 339 



General Relations of Minerals in Veins 340 



The Minerals of the Deposit 341 



Benitoite 341 



Crystallography 341 



Habits 344 



Symmetry 345 



Etch Figures 345 



Natural Etching 347 



Physical Properties 347 



Chemical Characters 349 



Benitoite as a Gem 353 



Neptunite 354 



Crystallography 354 



Physical Characters 356 



Chemical Characters 357 



Natrolite 357 



Copper Minerals 359 



Other Minerals 360 



Amphiboles 360 



Albite 361 



