WHITLOCK. — CRYSTAL FORMS OF CALCITE. 303 



X. (0887). This rhombohedron was first observed by Zippe 33 on 

 crystals from Andreasberg. It was subsequently noted by Hessen- 

 berg 34 and Sansoni 35 on several combinations from the same locality. 

 It also marks the intersection of the zone [0887-1120] which contains 

 a number of well established forms. The form should be regarded as 

 well established. 



Y. (0 • 19 • 19 • 13). This rhombohedron was observed by YYhitlock 36 

 on crystals from Lyon Mountain, N. Y. The form occurs on two of 

 the five types described, and on one of them (Type II) is developed 

 to the extent of a dominant habit. It lies close to (0332) and should 

 be regarded as somewhat doubtful. 



The following rhombohedrons lie in the portion of the zone between 

 (0332) and (0221): 



Form 



j p. a. f. t L. M. A. N. ip. 



J 032 0-11-7 085 0-13-8 053 074 095 0-11-6 021 

 Symbol | ¥ f ^ III ¥ 2 



— — i J J J 1 | 2 - 



V-2 — V b 4 • 3 2 2 



2d' 0JJ§1234» 



N 3 1 i | 1 • 2 3 (4) 



Referred to N 3 this portion of the zone is nearly complete and contains 

 the extra form -^ which would fall in normal series N 4 . 



N. (0- 11 -11 -6). This rhombohedron was noted by Thurling 37 on 

 crystals from Andreasberg. The form was established from good meas- 

 urements in the rhombohedral zone. The zone [0-11 -IT -6 : lOlO] is 

 well defined and the form, which occurs in normal series N 4 , may be 

 said to be fairly well established. 



In the portion of the zone lying between (0221) and OlIO) the most 

 prominent zone intersections occur at (0551) and (0-11-lT-l) Split- 

 ting the zone at these points as knots we have for the zone fragment 

 between (0221) and 0551): 



33 Zippe, F. X. M., loc. cit., Fig. 90. 



34 Hessenberg, F., loc. cit. 



35 Sansoni, F. R., loc. cit. 



36 Whitlock, H. P., N. Y. State Mus. Mem., 13, 81 (1910). 



37 Thurling, G., N. Jahrb. f. Min. B. B., 4, 327 (1886). 



