A. IF. Phillips — New Zinc Phosphates. 



277 



.y(120), is always well developed, but strongly striated verti- 

 cally. The alternations of growth between the prism and the 

 brachypinacoid are so marked, as to round this portion of the 

 prism zone almost circular. The pyramid, p (111), is present 

 on all the crystals and is the second best developed form. The 

 faces are rounded and striated parallel to their intersections 

 with the macropinacoid. The form is equally developed at both 

 terminations. The macrodome, ^/ (101), is small and variable, 

 and while the angle fixes the face, as the unit dome, in several 

 cases it appeared triangular, as if not in the same zone as 

 p, p '. This is caused by the rounded nature of the pyramid 

 faces and in the illustration the dome is shown as the unit 

 dome in contact with macropinacoid and its intersections with 

 the unit prism parallel. The com- 

 parative development of all the forms 

 is as represented in the illustration. 



Angles. — While to the eye the 

 various faces seemed perfect and 

 bright enough to yield reflections, 

 in the goniometer they give only 

 a confused blur, with no indication 

 of a signal whatever. The measure- 

 ments are, therefore, very imperfect, 

 measured mostly with a small Wol- 

 laston goniometer. The axial ratio 

 and crystal angles are only approxi- 

 mate. 



Average Limits No. 



s ^ s' (120) : (120) 80° 37' 79° 58' to 80° 50' 9 



a^d (100): (101) 50° 28' 49° 30' " 51° 25' 4 



(I ^ d' (101) : (101) 79° 24' 78° 20' " 80° 5' 3 



p^p' (111): (111) 77° 18' 76° 29' " 78° 30' 5 



Axial ratio a : b : c = 0-5S9 : 1 : 0-488. 



The combination of forms, the crystal angles and axial ratios 

 are very near that of hopeite as given by J. L. Spencer.* 



Chemical composition . — Several crystals were ground, com- 

 bined in one sample and analyzed with the following results : 



No. 1 No. 2 Theoretical 



ZnO 57'51 57-60 57'625 



P,0 5 28-77 28-88 2S-721 



H„0 1374 13-G8 13-653 



100-02 100-16 99-999 



*Mineralogical Magazine, vol. xv, p. 1. 



