I c 



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 



Second 



1 



Third 



Fourth 



Fifth 



Sixth 



Seventh Eighth 



.iN intn 







type 



type 



type 



type 



type 



type 



type 



type 



type 



0001 









X 















1 1 





A 



















1 1 20 



d 







A 



A 







X 





X 



IOI I 



r 















X 





X 



OI 12 



e 



X 



X 



X 



X 



X 



X 



X 



X 



X 



044_5 



I 













X 









O44I _ 



V 











X . 











O.I2. 12. 1 



T 













X 









8. i. 9. 10 



D 















X? 







6i75 



V 















X 







3!42 



A 

















X 





5-3-8.2 



T 

















X 





10.3. 13.2 



e 





X 



X 



X 



X 









X 



I5-4-19-3 



A 









X 













3. 16. 19. 2 



n 

















X 





SUMMARY OF MEASURED AND CALCULATED ANGLES" 











X 





r 



Z 



Forms 





0001 



A ohhl 



hkil 4 hikl 



hkil^ ikhl 



hkil x 



! khil 

























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° i6i' 















0441 _ 



V 



75° 43' 



75° 47' 















0.12. 12. 1 



T b 



85° i5 



85° 10J 















8. 1. 9. 10 



D 











7° 3°' 



7° 29*' 







6 175 



V 











12° 4 ' 



12° O' 



85° 54' 



85° 59' 



3 I42_ 



X 











24° 13' 



24° io' 



66° 39' 



66° 15*' 



10.3. 13. 2 



9 











25° 19' 



25° 5' 



39° i5i' 



39° 13' 



iS-4- 19-3 



A 







95° 3' 



95° 2' 



22° 43' 



22° 4 l' 



41° 44' 



41° 54' 



3. 16. 19.2 



n 











16° 46' 



16° 52' 



44° 56' 



44° 57*' 



n The 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- 



