WHITLOCK. — CRYSTAL FORMS OF CALCITE. 311 



from the point of view of zonal relations as the previous form should 

 be regarded as well established. 



a: (8- 1-9- 10) = (910). This scalenohedron was first recorded by 

 Zippe 56 on crystals from Andreasberg and was subsequently noted 

 by vom Rath 57 from Lake Superior, and by Sansoni 58 from Andreas- 

 berg. The zone [8- 1-9- 10 : 0110] is well marked and the form is 

 probable. 



/3: (9-1-10-11) = (10-1-0). This scalenohedron was observed by 

 Sansoni 59 on crystals from Andreasberg. The form occurs on com- 

 bination 249, Figure 19, in combination with (0112) and (8-1-9-10). 

 It marks the intersection of two minor zones containing several 

 prominent forms. The form may be ranked as well established. 



d: (13-1-14-15) = (14-1-0). This scalenohedron was observed 

 by vom Rath 60 on crystals from the trap of the Nahe basin. The 

 form was determined by approximate measurements on corroded faces. 

 Furthermore it lies very close to (1011) and falls in a high normal 

 series. The form should be classed as doubtful. 



Zone 4. Scalenohedrons of the Zone [1011 :1120] = [100:101] 



Symbol t . 



h 



In this portion of the principal zone the prominent zone intersec- 

 tions occur at the poles of the common scalenohedrons H : (3142) = 

 (301), K : (2131) = (201), P : (3251) = (302) and T : (3271) = 

 (403). Splitting the zone at these points we have for the forms 

 in the fragment between (100) and 301): 



5 6 Zippe, loc. cit. 



57 vom Rath, G., Pogg. Ann., 132, 137. 



58 Sansoni, loc. cit. 



59 Sansoni, loc. cit. 



60 vom Rathi G., Pogg. Ann., 135, 572. 



