I906.1 SMITH— PARAGENESIS OF MINERALS. 211 



The localities where garnet-glaucophane schists have been found 

 in California are too numerous to mention in detail, but the principal 

 occurrences from which they have been studied are : Camp Meeker, 

 Pine Flat, Junction School-house near Healdsburg, and Gurneville 

 in Sonoma County ; Tiburon Peninsula ; San Pablo ; North Berkeley ; 

 Mt. Diablo ; Arroyo Hondo in Calaveras Valley ; Oak Hill near San 

 Jose ; near San Luis Obispo ; Santa Margarita ranch in San Diego 

 County ; Santa Catalina Island. 



2. Glaucophane-epidote Schists. — This type of schist is even 

 more common in the Coast Ranges than the garnet-glaucophane 

 schist ; it is almost invariably associated with the greenstones, and 

 grades over into them. From the chemical nature and association 

 of the rocks it would seem that the glaucophane-epidote schists are 

 invariably the product of metamorphism of basic igneous rocks, or 

 possibly from basic tuffs. All the minerals in them are the product 

 of recrystallization, and if they were ever tuftaceous all evidence of 

 the original fragmental nature is obliterated. Becker^ described 



Analyses of Epidote-Glaucophaxe Schists. 



I. II. III. 



Si02 49.68 46.07 46.39 



AI2O3 13-60 15.35 17-34 



Fe203 1.86 3.61 • 6.32 



FeO 8.61 9.87 4.62 



MgO 6.27 • 7.83 4.93 



CaO 10.97 4-37 1307 



Na20 3.09 3.22 2.95 



K2O 0.12 2.68 0.25 



H2O (above 100° C.) . . 3.84 (above 110° C.) 4.25 (above 110° C.) 1.48 



H2O (100° C.) 0.00 (below 110° C.) 0.16 (below 110° C.) 0.08 



Ti02 1. 31 1.63 0.85 



MnO 0.04 trace trace 



P2O5 0.21 



C2O 2.24 



Total 99.60 100.09 100.52 



I. Epidote-glaucophane schist (98 Sulphur Bank, California) ; Melville, 

 analyst; Becker, Mon. XIII., U. S. Geol, Survey, p. 104. 



II. Epidote-glaucophane schist, Winston's Bridge, Oregon ; H. S. Wash- 

 ington, analyst, Amer. Jour. Sci., IV. Sen, Vol. XL. p. 53. 



III. Epidote-glaucophane schist. Kyperusa, Syra, Greece; H. S. W'ashing- 

 ton, analyst, Amer. Jour. Sci., IV, Ser., Vol. XL, p. 39. 



^ Mon. XIIL, U. S. Geol. Survey, p. 104. 



