238 



SMITH— PARAGENESIS OF MINERALS. 



[October 5 



XXVIII. Chlorite from glaucophane schist, San Pablo, California; W. C. 

 Blasdale, analyst. Bull. Dept. Geol. Univ. of California, Vol. II., p. 340. 



XXIX. Talc, from glaucophane schist, San Pablo, California; W. C. 

 Blasdale, analyst, lac. cit. 



XXX. Zoisite (or pale epidote?), from pseudodiabase; Melville, analyst; 

 G. F. Becker, Mon. XIIL, U. S. Geol. Survey, p. 79. 



Table of Analyses. 



XXXL Garnet, from omphacite eclogite. Coyote Creek, six miles north of 

 San Martin, Santa Clara County, California; W. O. Clark, analyst. 



XXXII. Lawsonite from glaucophane eclogite. Reed's Station, Tiburon 

 Peninsula, California; Schaller and Hillebrand, analysts, Amcr. Jour. Sci., 

 IV. Ser., Vol. XVIL (1904), p. i97- 



SUMMARY. 

 Glaucophane-bearing rocks have been made out of very dififerent 

 original materials. Siliceous fragmental sediments, deposits of 

 organic silica, acid arkoses, medium basic clay shales, and basic tuffs 

 have all been altered to a somewhat similar product. And igneous 

 rocks have contributed to a like result. Syenites, diorites, diabases 

 and gabbros, and probably pyroxenites have been changed into glau- 

 cophane schists. At first sight it would seem a hopeless task to 

 attempt to find out the origin of a glaucophane schist when it 

 might have been made from any one of these rocks. But, for- 

 tunately, the intrinsic character of the original rock has not been 

 altered, and the chemical readjustment consequent upon metamor- 



