i9o6.] SMITH— PARAGENESIS OF MINERALS. 213 



at the San Juan ]\Iine, Oak Hill near San Jose ; one mile south of 

 the mouth of Coyote Canyon, Santa Clara County ; and near Cayucas, 

 in San Luis Obispo County. At all these places this rock is associated 

 with epidote schists rather than with the garnetiferous type. 



V. Hornblende Schists. 



The hornblende schists do not make up independent rock-masses, 

 but occur in subordinate quantities, associated with eclogites. They 

 are ,of two principal types ; those composed of the green prismatic 

 actinolite, known as smaragdite, and chlorite, and those composed 

 largely of pargasite. Both contain glaucophane in varying amounts, 

 but the actinolite schists are characterized by the abundance of 

 chlorite, while the pargasite schists contain abundant epidote and 

 margarite. Carinthine occurs in both, especially where glauco- 

 phane is more abundant. As in all the basic schists of the glauco- 

 phane group, titanite is a common, and often an abundant con- 

 stituent. The pargasite schists also often show secondary albite, 

 but only in the rocks where little glaucophane is present. In both 

 actinolite and pargasite schists glaucophane occurs as replacement 

 rims around the more basic ferro-magnesian minerals. Both types 

 grade over into eclogites and into basic mica schists. 



The only analysis yet made of this group is that given by 

 Becker^ of a pseudodiorite. This analysis is quoted above, and shows 

 the rock to have been originally a diabase. Some of the actinolite 

 schists in the Coast Ranges are apparently still more basic, and 

 were probably made out of the pyroxenites, or at any rate out of 

 rocks very poor in feldspar. Slides of actinolite schist have been 

 studied from Camp Meeker in Sonoma County ; the Junction School- 

 house near Healdsburg ; Knoxville ; Tiburon Peninsula near Reed's 

 Station ; near San Pablo ; Arroyo Hondo at the north end of Cala- 

 veras Valley ; Oak Hill near San Jose ; a mile south of the mouth 

 of Coyote Canon, Santa Clara County ; on Coyote Creek, six miles 

 north of San Martin ; near the Hopkins reservoir, about three miles 

 southwest of Redwood ; near Cayucas, in San Luis Obispo County. 

 These schists also occur at many other places in the Coast Ranges 

 where no detailed study of them has been made. 



^ Mon. XIII., U. S. Geol. Survey, p. loi. 



