IO 



NEW YORK STATE MUSEUM 



which the natural etchings present on the prismatic planes, em- 

 phasize the twinning habit. Figures 18 and 19 show twin crystals 

 of the second type twinned according to both laws mentioned 

 above. Figure 20 shows a twin crystal of the third type. 



SUMMARY OF OCCURRING FORMS 



Forms 





First 

 type 



Second 

 type 



Third 

 type 



Fourth 

 type 



Fifth 

 type 



Sixth 

 type 



Seventh 

 type 



Eighth 

 type 



Ninth 

 type 



0001 



c 







X 















IOIO 



m 



X 



















1120 



a 







X 



X 







X 





X 



IOII 



r 















X 





X 



0112 



e 



X 



X 



X 



X 



X 



X 



X 



X 



X 



0445 



I 













X 









0441 



V 











X 











0.12. 12. 1 



T 













X 









8. 1.9. 10 



D 















X? 







6i75 



V 















X 







3!42 



A 

















X 





5-3-8.£ 

 10.3. 13.2 



T 



6 





X 



X 



X 



X 







X 



X 



I5.4.I9-3 



A 









X 













3. 16. 19. 2 



n 

















X 





SUMMARY OF MEASURED AND CALCULATED ANGLES'* 











X 





T 



Z 







0001 a ohhl 



hkil a hikl 



hkil^ ikhl 



hkil j_ khil 



Forms 





















meas- 



calcu- 



meas- 



calcu- 



meas- 



calcu- 



meas- 



calcu- 







ured 



lated 



ured 



lated 



ured 



lated 



ured 



lated 



OII2 



e 



45° 3' 



45° 3' 















0445 



I 



38° 6' 



38° i6f 















0441 



V 



75° 43' 



75° 47' 















0.12. 12. I 



T b 



85° i5 



85° ioi 















8. 1.9. 10 



D 











7° 30' 



7° 2 9 r 







6 i75 



V 











12° 4' 



12° O' 



85° 54' 



85° 59'' 



3 142 



A 











24° 13' 



24° 10' 



66° 39' 



66° 1 si' 



10.3. 13.2 



9 











25° 19' 



25° 5' 



39° 1 Si' 



39° 13' 



15.4.19-3 



A 







95° 3' 



95° 2' 



22° 43' 



22° 41' 



41° 44' 



4i° 54' 



3. 16. 19. 2 



n 











16° 46' 



1 6° 52' 



44° 56' 



44° 5-7*' 



oThe scalenohedron (5382) was identified by means of measurements taken with a contact 

 oniometer. 6New. 



CALCITE FROM UNION SPRINGS, CAYUGA CO. 



In the summer of 1899 Dr John M. Clarke, then State Paleontol- 

 ogist, found at Union Springs some extremely interesting crystals 

 of calcite. Several specimens of these were sent to Yale Univer- 



