24 NEW YORK STATE MUSEUM 



i Marcasite from Rondout showing prevailing habit of crystals. 

 Forms: c (ooi), m (no), e (ioi),/(on), 5 (in). 



2 Marcasite from Rondout, showing repeated twinning. Forms: 

 c (ooi), m (no), e (ioi), / (on). Figures i and 2 are shown 

 with b axis vertical. 



3 Pyrite from Rondout, showing cube twinned parallel to (no), 

 producing L-shaped form. 



4 Pyrite from Rondout, showing scepter crystal. 



5,6 Quartz from Rondout, showing penetration twins on twinning 

 axis c. Forms: m (1010), r (ion), m (6065), * (5053), z 

 (0111), 5 (1121), v (7181), e (1231). 



7 Calcite from Rondout showing crystals of the second type. 

 Forms: A (15. 4. 19. 3), e (0112). 



8 Calcite from Rondout showing crystal of the third type. Forms : 

 c (0001), a (1120), e (0112) A (15.4.19.3). 





