474 .1. //. Phillips— Some New Forms of Natrolite. 



were all that could be desired. The measurements for this 

 face were <f> = 63° 58' and p = 90°. The average value of 

 these angles, yielded by the ten brightest signals, is: 



<p p Maximum Minimum 



."Measured 63° 50' 90° 64° 11' 03° 4(i' 



Calculated... 63° 52' 90° 



The prisin r(120) was represented by two narrow faces on 

 one crystal which yielded fair reflections : 



P 



90° 

 90° 

 Calculated 18° 40' 90° 



Measmed . 



j 18° 00' 

 "j 18° 36' 



The pyramid o(151) was measured 1G times and was repre- 

 sented on 4. crystals. The signals varied with the size of the 

 face; taking the average of eight measurements where the sig- 

 nals were satisfactory, the angles are, 





tb 



P 





<t> 



P 



Measured.. 



11° 33' 



60° 54' 



Maximum.. 



11° 42' 



61°05' 



Calculated . 



11° 31' 



60° 49' 



Minimum .. 



11° 27' 



60° 46' 



The pyramid £(531) was represented by three faces on one 

 crystal, two of which were well developed, yielding satisfac- 

 tory reflections, while the third was very small with an indis- 



tinct signal. 









<t> 



P 



Measured. 



J 59° 25' 



"j 59° 23' 



64° 31' 

 64° 31' 



Calculated 



59° 29' 



64° 22' 



There were several other forms represented, by very small 

 faces, yielding signals too dull or indistinct to give satisfactory 

 measurements. The best of these, which occurred several 

 times, indicated a pyramid in the zone of the new prism 

 <?(210), with indices (211). 



Princeton, N. J., Oct. 9, 1916. 



