WHITLOCK. — CRYSTAL FORMS OF CALCITE. 305 



on crystals from the trap region of New Jersey, and was identified by 

 the fact that its planes truncated the polar edges of (17- 11-28-6) 

 in the negative sextants. Like the preceding form discussed, it falls 

 in normal series N5. It also lies in a somewhat well marked zone 

 [0- 13-13 -4 :2110]. The form may be regarded as probable. 



A. (0992). This rhombohedron was noted by vom Rath 44 on 

 crystals from Andreasberg in combination with (11 -8 -19 -3), the polar 

 edges of which it truncates in the negative sextants. It falls in normal 

 series N5 and may be regarded as probable. 



The zone fragment between (0551) and (0-11-Tl-l) contains the 

 following forms : 



A e> 



v (3. Q. n. B. 2. 



rorm (051 071 081 091 0-11-1 



Symbol 5 7 8 9 11 



v-2 — v J 



N 2 J 1 2 



Referred to No this section of the zone is complete. 

 The zone fragment between (0-11-TI-l) and (OlIO) contains the 

 following forms: 



\ 2. C. $. *. tt. T. U. m 



orm Jo-11-1 0-13-1 0-14-1 0-17-1 0-20-1 0-28-1 0-36-1 010 

 11 13 14 17 20 28 36 



nil 1 3 17 25 



u 3 2 y "2" 6 6 



\ i • 1 §•(?)•• (f) - 



This section of the zone is incomplete and contains the extra forms 

 28 and 36. 



T. (0-28-28-1). This rhombohedron was noted by Thurling 45 on 

 one specimen from Andreasberg. Although the observations of the 

 author cited agree very closely with theory, it is significant that the 

 rhombohedron (0-29-29-1), the p value of which varies only 4' from 

 that of (0-28-28-1), corresponds to much simpler_ Miller indices 

 [(0-29-29-1) = (10-10-19), (0-28-_28-l) = (29-29-o5)] and lies in 

 normal series N 3 . The form (0-28-28-1) should be regarded as doubt- 

 ful. 



44 vom Rath, G., Pogg. Ann., 132, 517 (1867). 



45 Thurling, loc. cit. 



