11(> 0. Bowles— Crystal Forms of JPyromorphite. 



hollow. The prismatic faces give fairly definite reflection 

 figures in the goniometer, and hence the convergence toward 

 the point of attachment is not due to curvature, but is attained 



The forms 



iioio}, 



! 000 1|, and 



{1011 I 



by a series of steps. 

 were observed. 



The observed and calculated angles of the new forms are 

 given below in tabular form. 



Form 



h { 21 30 * 

 u {2131} 



Observed Calculated 

 19° 11' 19° 06' 



18° 58' 



19° 06' 



Observed Calculated 



89° 55' 90° 00' 



66° 02' 66° 02' 



Fig. 2 represents all the known crystal forms of pyromor- 

 phite, and the following table gives the characteristic angles. 

 Those for which no reference is given are taken from Gold- 

 schmidt's " Krystallographische Winkeltabellen." 









Table oi 



Angles. 





Form 







9 



Form 



c 



{0001} 



. 



0° 00' 



y {2021} 



m 



■jiolo} 



0° 00' 



90° 00' 



it {4041} 



a 



{1120} 



30° 00' 



90° 00' 



P{8081}§ 



h 



{2130}* 



19° 06' 



90° 00' 



R{90Sl}{ 



e 



;3034{f 



0° 00' 



32° 31' 



s {1121} 



X 



{1011} 



0° 00' 



40° 22' 



u {2131}* 



b 



15.0.15.14! 



t 0° 00' 



42° 37' 





0° 00' 59° 32' 



0° 00' 73° 36' 



0° 00' 81° 38' 



0° 00' 82° 34' 



30° 00' 55° 49' 



19° 06' 66° 02, 



Department of Geology and Mineralogy, 

 University of Minnesota, 



Minneapolis, Minn., May 4, 1911. 



* New forms. 



f Bowles, this Journal, vol. xxviii, p, 40. 



% Lacroix, Bulletin de la Socie'te' Mine"ralogique, 1894, p. 120. 



§ Lacroix, Mineralogie de la France, iv, p. 394. 



