I906.J SMITH— PARAGENESIS OF MINERALS. 209 



The chemical relations of the group of rocks and their trans- 

 formation into glaucophane-bearing schists or gneisses are fully 

 discussed below, in the section on " chemical readjustment in the 

 metamorphism of the glaucophane-bearing rocks." 



Analysis of Quartz Diorite from Oak Ridge, Fwe Miles East of Calveras 



Valley, with Secondary Crossite and Lawsonite. 



W. O. Clark, Analyst, 



SiOa 61.55 



AI2O3 17.48 



FcoOs 1.49 



FeO 3.50 



MgO 3.00 



CaO 3.12 



Na^O 8.47 



K2O 0.07 



H2O (—110° C.) 0.12 



H=0 {+ 110° C.) 1.21 



TiO^ 0.28 



Total 100.29 



IV. Glancophane Schists. 



I. Glaucophune .garnet schists. — The normal type of glauco- 

 phane schists, those with glaucophane, actinolite, pale epidote and 

 garnet as the principal constituents, is widely distributed in the 

 Coast Ranges. They are thin bedded, foliated and crumpled, show- 

 ing intense crushing and shearing. All the minerals in them are the 

 products of recrystallization, sometimes of igneous rocks, and some- 

 times of clay shales, possibly also of basic tuffs. The glaucophane is 

 usually in the form of long blades and needles, the epidote in short 

 thick-set prisms, and the garnet in dodekahedrons. Actinolite is an 

 almost invariable companion of the glaucophane, and titanite is 

 present in irregular patches, rarely in good crystals. This type of 

 glaucophane schist is often associated with eclogite, and grades 

 over into it, which shows that. at least some of the holocrystalline 

 basic metamorphics were made out of igneous rocks. Some of the 

 garnet-glaucophane schists, however, are thought to have been made 

 out of ferruginous clay shales, and Becker^ says that a transition 

 from the glaucophane schist to little altered shale was observed in 



' Mon. XIII., U. S. Geol. Survey, p. 102. 



