Waring — Quartz from San Diego County, California. 127 



Deformation, or abnormal growth, is also met with. Fig. 6 

 is an example of parallel growth, while figs. 8, 9 and 10 are 

 distorted forms. In fig. 10 the crystal is placed with its major 

 axis perpendicular to the paper, so that one is looking down 

 on the apex of the pyramid. 



Corrosion or etching of the pyramidal faces, while those of 

 the prism are unaffected, is illustrated in figs. 11 and 12. 



3b. 



lb. 



Orthographic and clinographic projections of quartz crystals 

 from Kincon, California, from figs. 3 and 1, p. 126. 



One other extremely interesting point is that of the evidence 

 of secondary crystallization, as shown by the filling up of the 

 x, y, and e-M faces to a level, or nearly so, with the prism face. 

 This is well exhibited in figs. 5 and 10. 



While the s face occurs rather commonly elsewhere, the x 

 and y faces are of much rarer occurrence. It is therefore 

 worthy of note that upon the crystals of this region it is the 

 trapezohedral faces that develop most frequently, while the s 

 face, the trigonal pyramid, is seldom found. 



Stanford University, California. 



