i9o6.] SMITH— PARAGENESIS OF MINERALS. 219 



gneiss has normal glaucophane instead of crossite. Ransome^ has 

 also published an analysis of a quartz glaucophane schist or gneiss 

 from Angel Island, but it is impossible to tell from the context just 

 which rock was analyzed. The analysis is quoted below. 



A massive quartz glaucophane gneiss has been observed about 

 a mile and a half southwest of Belmont. This rock is almost exactly 

 like that described from near Pine Flat, except that no actinolite was 

 found in the slides, and that the glaucophane is mostly in radial 

 aggregates. 



Similar massive quartz glaucophane gneisses have been studied 

 from the Arroyo Hondo at the north end of Calaveras Valley ; 

 from Oak Hill near San Jose ; and from near Cayucas in San Luis 

 Obispo County. In the rock from the latter locality striated feld- 

 spar, probably albite, is rather common. Washington'^ has de- 



Analysis of Quartz Glaucophane Gneiss. 



I. II. III. 



Si02 82.53 80.21 74.48 



AI2O3 6.88 7.99 9-15 



FesOs 0.59 3-35 i-4i 



FeO 4.11 412 



MgO 1.86 1.54 3-04 



CaO 0.68 1. 10 2.84 



NasO 1.21 5.97 2.24 



K2O 1.24 0.22 0.43 



H2O (110° C.) 1.35 loss on ig. 0.74 (+ 110° C.) 2.06 



H2O (110° C.) 0.07 (— iio°C.) 0.08 



MnO trace 



Total : 100.52 101.12 99.85 



I. Quartz glaucophane schist, Four Mile Creek, Oregon; Washington, 

 analyst; Amcr. Jour^ Sci., 4th Ser., Vol. XL, p. 53. 



II. Quartz glaucophane schist, Angel Island, California ; Ransome, an- 

 alyst; Bull. Dcpt. Gcol. Univ. of California, Vol. I., 231. 



III. Quartz glaucophane schist. Little Harbor, Catalina Island, California; 

 Washington, analyst; Amcr. Jour. Sci., 4th Ser., Vol. XL, p. 48. 



scribed a quartz glaucophane gneiss from Little Harbor, on Catalina 

 Island. The rock is fissile, composed of a groundmass of granular 

 quartz, with numerous crystals and needles of glaucophane, and a 

 few zircons and epidotes. No garnets are mentioned as occurring in 

 this rock, and their absence is unusual in quartz glaucophane gneiss. 



^Op. cit., p. 231. 



^Avicr. Jour. Sci., IV. Ser., Vol. XL (1901), p. 48. 



