338 University of California Publications in Geology [Vol. 10 





Measured 





Calculated 



No. of 



Forms 







P 



< 



P 



P 



measurements 



u T44 



8 09 



44 16 



7 



55 



44 19 



11 



122 



30 38 



47 24 



28 



57 



48 09 



1 



fa 122 



19 02 



45 14 



20 



41 



45 58 ' 



1 



w 142 



15 35 



62 51 . 



16 



05 



63 35 



1 



e T42 



IT 04 



62 57 



To 



41 



63 05 



1 



Aii analysis of the clear crystals gave : 



SiO, 50.42% 



CaO 48.29 

 MgO 0.60 

 Fe,0 3 0.51 

 Ign. 0.07 



99.89 



The optical data were kindly determined by E. S. Larson of the 

 U. S. Geological Survey: 



a = 1.614; /3= 1.629; -, = 1.631; 2E = 58°±'5°; 2V = 35°±4°; 

 Y II fibers; Z 1 fibers. Parallel extinction; dispersion per- 

 ceptible p>i>. 



The indices are close to those for pure artificial wollastonite : 

 o = 1.616; /3 = 1.629; y = 1.6321; 2V = 39°. 



Vesuvianite. — Massive vesuvianite is very common in the meta- 

 morphic zones between the monzonite dikes and limestone. It is in- 

 timately associated with garnet and diopside. Most of this massive 

 variety has a light yellowish color and shows broad crystal faces. 

 Simple crystals of this yellow color are also common, some of them 

 being very perfect. The blue caleite contains crystals of a darker 

 brown color with brilliant faces and somewhat fused appearance. 



Two general habits of the crystals are prominent. The simpler 

 type consists of the doubly terminated pyramid without any modifying 

 faces on the edges, as illustrated in figure 6, plate 24. Occasionally 

 the edges of these are truncated by the second-order pyramid as 

 narrow faces, and a small base may also be present. The sizes of these 

 crystals range from less than one-fourth centimeter to more than six 

 centimeters in width. All of them are of the light yellow color and 

 they are associated with the white crystalline limestone. 



The second type consists mainly of the unit bipyramid (111) and 

 second-order prism (100) in about equal development, as shown in 

 figure 7. This type is often modified by very small planes on the edges 

 and on the points of the lateral axes, making a more general combina- 

 tion, as illustrated in figure 8. These crystals have a dark brown 



