28 NEW YORK STATE MUSEUM 



15 Calcite from Rondout, showing the development of pyrite in- 

 clusions on crystals of the eighth type. 



16 Calcite from Rondout, showing crystal of the ninth type (rhom- 

 bohedral habit). Forms: a (11 20), r (ion), e (0112), A 

 (15.4.19.3). 



17-20 Calcite from Rondout showing twin crystals. Figure 19 

 is drawn with the twinning plane e (01 12) vertical. 



