UNIVERSITY OP CALIFORNIA 



Bulletin of the Department of Geology 



Vol. I, No. 10, pp. 301-312, PI. 17. ANDREW C. LAWSON, Editor 



ON 



LAW SO N I T E 

 A NEW ROCK-FORMING MINERAL 



FROM 



THE TIBURON PENINSULA, MARIN COUNTY, CALIFORNIA* 



BV 



F. Leslie Ransome 

 Fellow in the University of California. 



CONTENTS. 



Page. 



Occurrence 301 



Crystal Form 302 



Optical Properties 305 



Chemical Composition 307 



General Physical Properties and Blowpipe Reactions 308 



Place of Lawsonite in Classification 309 



Associated Minerals 309 



OCCURRENCE. 



The mineral for which the writer proposes the name lawsonite, 

 in honor of Prof. Andrew C. Lawson, occurs as an important rock- 

 making constituent of a rather massive outcrop of crystalline schist, 

 which is exposed near the periphery of an extensive sheet of ser- 

 pentine, on the Tiburon Peninsula, at a point about half a mile in 

 an easterly direction from Reed Station, on the line of the San 

 Francisco and North Pacific Railroad. 



* The writer takes sincere pleasure in according to his friend, Dr. Charles 

 Palache, the credit of a simultaneous discovery of the new mineral here 

 described, and in acknowledging the courtesy and generosity shown by him. 

 Dr. Palache found the mineral in his thin sections, while making a petro- 



