i9o6.] SMITH— PARAGENESIS OF MINERALS. 187 



original rock has had no influence on its formation. Naturally 

 glaucophane is more abundant in the basic metamorphics, where 

 there was more iron and soda necessary for its genesis. 



A rare variety of glaucophane has been described by Palache^ 

 from the Coast Ranges under the name of crossite. This differs 

 from common glaucophane chiefly in the orientation of the axes of 

 elasticity, the plane of the optic axes being transverse. The pleo- 

 chroism is the same as that of glaucophane, except that the colors 

 are more intense. The polarization colors appear to be lower than 

 those of glaucophane. There appears also to be a chemical differ- 

 ence, as will be seen in the analyses quoted below, the iron being 

 higher and the alumina lower than in any published analyses of 

 glaucophane, except three from Rhodus, described by H. B. Foullon^ 

 as rhodusite, a variety of glaucophane. Foullon, however, did not 

 give the optical orientation of the mineral, but stated that it lacked 

 the violet pleochroism so characteristic of true glaucophane. It is 

 probable that the mineral from Rhodus is either crossite or croci- 

 dolite. But since we have only one analysis of crossite, it is hardly 

 proper to base conclusions on that. 



Crossite has been identified in the Coast Ranges only in the 

 albite-crossite gneiss from North Berkeley, in a quartz-glaucophane 

 schist from Tiburon peninsula about a mile and a half north of the 

 ferry, and in a metamorphosed quartz diorite from Oak Ridge, 

 Santa Clara County, five miles east of Calaveras Valley. The last 

 two occurrences were identified solely by the optical orientation, 

 the analysis published by Palache being of the mineral from North 

 Berkeley. 



In some of the more ferruginous schists there is an asbestiform 

 glaucophane-like mineral that is probably crocidolite, and a probable 

 Tdentification of this mine-ral has also been made in a dynamically 

 metamorphosed albite syenite from Spanish Peak, Plumas County, 

 where a brownish titaniferous hornblende (kataphorite) has frayed 

 out at the ends in fine blue needles of crocidolite, with the charac- 

 teristic pleochroism of that mineral. 



^ " On a Rock from the Vicinity of Berkeley Containing a New Soda- 

 Amphibole," Bull. Dcpt. Gcol. Univ. Calif., Vol. I., pp. 181-192. 

 ^ Sitzb. Akad. Wien (1891), Bd. 100. pp. 172-174. 



