WHITLOCK. — CRYSTAL FORMS OF CALCITE. 347 



D (21 -5 -26 -18) = (65-2-13). This scalenohedron was observed 

 by Whitlock 143 on crystals of the second type from Kelley's Island, 

 Ohio. This form was identified from four series of consistent measure- 

 ments. It is, however, apparent from a consideration of the zonal 

 relations that the indices (8- 2-10-7) = (25-1-5) present a much 

 better agreement than those originally assigned. The pole of the 

 latter form falls at the intersection of the zones (6175 : 0221] and 

 [4223 : 1121]. Moreover the calculated angles for (8-2- TO- 7) agree 

 almost as well with observation as do those of (21-5-26-18). The 

 indices (8-2-10-7) should be substituted for (21-5-26-18). 



e 3 (4372) = (13 • 1 • 8) . This scalenohedron was recorded by Flink 144 

 on crystals from Langban, Sweden. As shown on Flink's figure this 

 form lies in the zone [2131 : 2461 : OlTO] which developed between the 

 poles (2131) = (201) and (2461) = (313) gives: 



Forms 201 13-1-8 715 514 23-5-19 827 313 



7 5 23 8 i 



4 7 



6 



3 o 15 



2 «J 4 



1 1 3 



2 L 4 



2 



From which development it will be seen that (4372) fall in normal 

 series N5. It also lies in zones [0332 : lOlO] and [0552 : 5051] both of 

 which are well marked. The form is probable. 



e l (14- 7 -21-12) = (47-9-16). This scalenohedron was also re- 

 corded by Flink 144 on crystals from the same occurrence as the pre- 

 ceding. The zonal relations of this form are very poor, which coupled 

 with the high Miller indices seem to render the form somewhat doubt- 

 ful. It is noteworthy that the hypothetical form (8-4-12-7) = (913) 

 meets the critical requirements of zonal relations and rational Miller 

 indices much better than (14-7-21-12), has the same value for the 

 *p angle and differs in p value from the latter form by only 12'. It is 

 possible that (8-4-12-7) should be substituted. 



h' (16-14-30-5) = (12-1-8). This scalenohedron was observed 

 by Flink _ 145 on_crystals from -Langban, Sweden. The form lies in 

 zones [5261 : 2461] and [5052 : 3251] and corresponds to quite simple 

 Miller indices. It is fairly probable. 



143 Whitlock, H. P., S. of M. Quarterly, 31, 231 (1910). 



144 Flink, Arkiv. f. Kemi. Min. Geol., 3, Fig. 155, 156 (1910). 



145 Flink, Arkiv. f. Kemi. Min. Geol., 3, Fig. 174 (1910). 



