306 S. L. Pen field — Crystallization of Willemite. 



Figures 1 and 2 represent the ordinary developments of the 

 faces. The rhombohedron of the second order, u was ob- 



'■& e 



served intersecting both extremities of the vertical axis and 

 always in the position required by rhombohedral tetartohedrism. 

 The rhombohedrons z and v are of rare occurrence. All of 

 the forms which have been observed are represented in the 

 basal projection, fig. 3. Among a suite of specimens from 

 this locality in the cabinet of the late Prof. F. A. Genth, sent 

 to the writer by Dr. F. A. Genth, Jr., only the simple combi- 

 nation of prism and basal plane was observed. 



The crystals are brilliant and give good reflections, but the 

 faces are commonly vicinal, which renders the measurements 

 somewhat uncertain. There was a decided tendency for the 

 basal plane to develop into a flat vicinal rhombohedron, while 

 the prism seemed always to be slightly warped or twisted. 

 Although the measurements of similar angles show a consider- 

 able variation, the best of them, judging from the character of 

 the signals, agree closely with the values calculated from the 

 fundamental measurement of Levy, p^p, 3031^0334=51° 30'. 

 It was decided, therefore, to retain his axial ratios, a : c — 



1:0-6696. 

















The 



following is a list of 



some 



of the calculated 



and meas- 



ured angles. 



























Number 















Average 



of times 











Calculated, measurement. 



measured. 





Limits. 





c s^e, 



0001^0112 = 21° 



8' 



21° 



6' 



11 



20° 



40'-21 c 



28' 



e^e', 



0112^1012 = 36 



23 



35 



48 



11 



35 



5-36 



24 



ay\e, 



1120^0112 = 71 



48 



71 



39 



7 



71 



14-71 



57 



r /\e, 



1011^0112 = 31 



59 



32 



2 



7 



31 



36-32 



38 



*■ Afi', 



IOIIa.1012 = 58 



51 



58 



45 



2 



58 



25-59 



5 



G A»*, 



0001/^1011 = 37 



m 



37 



56 



1 









C /\Z, 



0001 yvO 111 =37 



m 



37 



57 



1 









e /\u', 



0112^1213 = 11 



45^ 



11 



25 



3 



11 



21-11 



27 



e ^k, 



0112,^2113 = 31 



36" 



31 



51 



1 









C A«,' 



0001 A.21I3 = 24 



o 



23 



24 



1 









Us^tl', 



2113^1213 = 41 



20 



40 



49 



1 









e /v«, 



0112^1325 = 7 



7 



7 



23 



1 









