PALACHE. — CRYSTALLOGRAPHY OF LEADHILLITE. 459 



<p p 



Crystal 14 —81° 43' 62° 40' poor. 



" 14 -80 07 62 30 fair. 



" 17 -81 34 62 36 " 



Calculated —81 40 62 29 



% i # (256). Observed as a distinct face with good reflection on a 

 single crystal, in the zone [012 A 122]. Position good. 



<t> P 



Crystal 14 25° 00' 45° 35' fair. 



Calculated 25 01 45 39 



*, \ | (234). Observed as a distinct face with good reflection on 

 the same crystal as the last, in the zone [ill A 123]. Confirmed by 

 its good position. 



<t> p 



Crystal 14 37° 33' 46° 24' good. 



Calculated 37 42 46 30 



12, J | (132). Observed with two faces on one crystal and one on a 

 second, small and with poor reflections. Accepted, however, because 

 of its good position and place in an important zone. 



<t> p 



Crystal 10 21° 17' 60° 50' poor. 



"10 21 09 61 00 fair. 



"11 21 12 60 53 poor. 



Calculated 21 08 60 47 



®> I. 2 (536). Observed but once as a distinct face with fine re- 

 flection. The position is not wholly satisfactory. 



<P P 



Crystal 15 —56° 49' 45° 02' fair. 

 Calculated -56 29 45 12 



0, I | (768.) Observed but once as a large distinct face with per- 

 fect reflection. The position of the face is extremely close to that of 

 the common form q (2~ 12.) in twin position ; but as the crystal on 

 which it occurs shows no other indications of twinning, as the form 

 lies in the important zone [2"01 A 122], and as the measured angles 

 agree more closely with the calculated position of this form than with 

 those of q in twin position, the form is regarded as assured despite its 



somewhat complex symbol. 



<p p 



Crystal 10 -52° 57' 54° 16' perfect. 



Calculated, twin of q —53 17 54 05 



Calculated (768) —52 56 54 09 



