1 88 



University of California. 



LVoi. [. 



color and pleochroic. Its fibration is always parallel to the chief 

 axis of the amphibole crystal to which it is attached, and the two 

 minerals are in parallel position and in crystallographic continuity. 

 Measurements for extinction of clinopinacoidal sections of amphibole 

 and attached actinolite showed for the former an angle of 13 , for 

 the latter I7°-i8°. The optic orientation is normal, b=% c:c = 

 I7°-i8° behind. The pleochroism is in shades of green. The 

 absorption formula is C > 6 > 0. 



Chemical Characters. — The amphibole was separated from the 

 rock by means of Klein's solution for chemical analysis. The 

 powder thus obtained was examined under the microscope, and 

 found to be quite free from- attached feldspar. Single fragments 

 thus obtained gave a specific gravity of 3.16, while a solution in 

 which part of a large number of fragments fell, and part floated, gave 

 3.126. These figures may be considered as limits for its specific 

 gravity. Before the blowpipe fragments melt readily to a grayish 

 magnetic bead, and afford a strong flame reaction for sodium. The 

 hardness of the mineral is between 5 and 6, and its streak a pale 

 blue. 



For the following chemical analysis the writer is indebted to 

 Mr. W. S. T. Smith. It was executed on some two grammes of 

 carefully purified material, in the mineralogical laboratory of the 

 University of California: — 











Atomic 



Atomic 













Quotients. 



Ratios. 





SiO, 



55.02 



Si 



25.71 



.9182 



21.35 say 



21 



A1A 



475 



Al 



2.52 



.0932 



2.17 " 



2 



Fe 2 3 



10.91 



Fe 



7.46 



•1335 



3-1 1 " 



3 



FeO 



9.46 



Fe 



7-36 



.1317 



3.07 " 



3 



MnO 



trace 













MgO 



9-30 



Mg 



5.58 



•233 1 



5-37 " 



5 



CaO 



2.38 



Ca 



1.70 



.0426 



1. 00 " 



1 



Na,0 

 K 2 



7.62 

 •27 



Na 

 K 



5.66 

 ■23 



•2459 ) 

 .0058 J 



5-83 " 



6 



H 2 



11 ndet. 







43-21 



2-743 



6399 " 



64 



99.70 



100.00 



