WHITLOCK. — CRYSTAL FORMS OF CALCTTE. 345 



Positive Scalenohedrons not Previously Included. 



L (22- 8-30-37) = (89-23-1). This scalenohedron was observed 

 by Thiirling 132 on crystals from Andreasberg. In the combination 

 cited by Thiirling the form occurs as the inner kernal of a compound 

 crystal of scalenohedral habit, the form in question projecting through 

 the terminating planes (1235) of the outer individual. The planes 

 were described as smooth and brilliant. It is, however, noteworthy 

 that the pole of (22-8-30-37) falls very close to that of the common 

 scalenohedron (3145) of zone 4 and may possibly be vicinal to it. 



21 (7-6-13-2) = (22-1-17). This scalenohedron was recorded by 

 Johansson 133 on crystals from Norberg, Sweden. The pole of the form 

 lies at the intersection of several well marked zones, as [5051 :8- 

 14-22-3], [0331 :4371] and [2021 : 4481] and should be classed as 

 probable. 



b (20- 11 -31 -15) = (33 -2-9) \ _ scalenohedrons were 



a (37-19-56-21) = (38-1*18)5 ihese tW ° scalenonedlons * ere 

 observed by Palache 134 on several crystals from the Lake Superior 

 region of Michigan. They, together with ft> (7 -4 -IT -6) as previously 

 discussed, lie in zone [1012 : 2131] not [R : R3] as given by Palache. 

 The good quality of the faces which served to determine these forms 

 and the excellent zonal relations should serve to class both forms as 

 probable. 



M (8-4 -12 -5) = (25-1 -IT). This scalenohedron like the two last 

 was observed by Palache 135 on one crystal from the Lake Superior 

 region. The planes were relatively large and well developed and the 

 zonal relations very good. The form is well established. 



33 (10-5-15-4) = (29-1- 16)! This scalenohedron was observed 

 by Sansoni 136 on crystals from Blaton, Belgium, and by Cesaro 137 on 

 crystals from Rhisnes, Belgium. Cesaro points out that the measure- 

 ments obtained by Sansoni correspond better to the form (26-13-39- 

 10) but emphasizes the fact that these latter indices do not fall in the 

 zones [50ol : 0552], [5052 : 5382] and [0001 : 2130], which zonal rela.- 



132 Thiirling, G., N. Jahrb. f. Min. B. B., 4, 327 (1886). 



133 Johansson, K., Geol. Foren. Forh., 14, 49 (1892). 



134 Palache, C, loc. cit., Fig. 5. 



135 Palache, C, loc. cit., Fig. 9. 



136 Sansoni, F., Bull. Ac. Belg., (3), 9, 287 (18S5). 



137 Cesaro, G., Ann. Soc. Geol. Belg., 16, 165 (1889). 



