I906.J SMITH— PARAGENESIS OF MINERALS. 221 



I. II. 



SiO, 65.91 61.55 



AI2O3 11.62 17.28 



FcoOs 2.21 1.49 



FeO 5.30 3.50 



MgO 1.92 3.00 



CaO 5.89 3.12 



Na^O 1.95 8.47 



K2O 0.04 0.07 



H2O (100° C.) 0.28 0.12 



H2O (red heat) 4.38 1.21 



MnO trace trace 



TiOs 0.17 0.28 



Total 99.67 100.12 



I. Lawsonite glaucophane gneiss, three miles west of Redwood ; W. O. 

 Clark, analyst. 



II. Diorite with secondary crossite and lawsonite. Oak Ridge, five miles 

 east of Calaveras Valley; W. O. Clark, analyst. 



A lawsonite glaucophane gneiss very similar to that above de- 

 scribed occurs a mile south of the mouth of Coyote Canyon, Santa 

 Clara County, associated with lawsonite glaucophane schist. No 

 chemical analysis was made, but the slides show the same minerals 

 in about the same proportions. The original rock was probably a 

 diorite, or at least a medium basic rock rich in lime. 



Genetic Classification of the Glaucophane Rocks of 



California. 



•I. Certainly Original Sediments. 



A. Quartz glaucophane schists, gneisses and altered cherts, at 

 Pine Flat ; Junction School-house near Healdsburg ; Tiburon Penin- 

 sula ; Angel Island ; one mile west of Belmont ; Arroyo Flondo at 

 the northern end of Calaveras Valley ; near Cayucas in San Luis 

 Obispo County ; Oak Hill near San Jose ; and Catalina Island. 



B. Altered tuiTs and arkose ; lawsonite and epidote glaucophane 

 schists at the San Juan Mine, Oak Hill near San Jose, apparently 

 derived from a tuff which occurs unaltered nearby ; epidote glauco- 

 phane schists of North Berkeley ; orthoclase glaucophane gneiss 

 from Melitta near Santa Rosa, interbanded with quartzites. 



C. Altered clay shales ; basic glaucophane schists grading over 



