WHITLOCK. — CRYSTAL FORMS OF CALCITE. 293 



SF (10-1-Tl-O). This prism was observed by Schnorr *_on material 

 from Neumark, Germany. It lies in zone [0001 :1(M- 11 -3:40 -4 -44 

 : 9:10- 1-11-0]; the two intermediate forms (10- 1-11 -3) and (40-4- 

 44 • 9) were observed by Palache 5 on crystals from Lake Superior 

 and seem rational and well established. 



a (7180). This prism was observed by Whitlock 6 on crystals 

 from Bergen Hill, N. J. It lies in a vertical zone containing (7189), 

 (7186) and (14-2-TB-3) and also in the very well marked zone [1102- 

 1780] containing no less than 13 intermediate forms. The form is 

 probable. 



j (7- 6-13-0). This prism was observed by Schaller 7 on crystals 

 from Andreasberg. It lies in the vertical zone which contains the 

 forms (14- 12-26-5) and (7-6-L3-2). On the whole this form seems 

 less probable than either of the two preceding ones. 



Hypothetical Prism. Referring to N 2 in the above development, 

 it will be noted that the term 2, corresponding to \, is absent from 

 the series. The hypothetical prism which would yield 2 in this series 

 would have the indices (3250) = <*> R5. Although not strongly 

 marked the vertical zone [0001-3250] contains the forms (3257), 

 (3254) and (3251). 



h 

 Zone 2 — Pyramids of the Second Order. Symbol ,• 



Using the Bravais-Miller indices and suppressing the third term, 

 the zone of the second order pyramids contains the following forms : 



4Schnorr, Programm d. Realgym. Z. Zwickau, p. 6 (1896). 



5 Palache, C, Geol. Surv. Mich., 6, 161 (1900). 



6 Whitlock, H. P., N. Y. State Mus. Bull., 133, p. 217. 



7 Schaller, W. T., Zeit, f. Kryst., 44, 321 (1908). 



