3 2 NEW YORK STATE MUSEUM 



27 Calcite from Union Springs, showing crystal of the first genera- 

 tion, transitional in habit between the pyramid-scalenohedral 

 type [Fig. 23], and the rhombohedra^ type [fig._ 28], Forms: 

 m (1010), a (ii2o) 2 _y (8.8.16.3), r (ion), M (4041), e (0112), C 

 (6178), X (81.41.122.40). . 



28 Calcite from Union Springs, showing crystal of the first genera- 

 tion_ of rhombohedral habit. Forms :_a (1120), y (8.8.^.3), 

 r (ion), M (4041), e (0112), X (81.41.122.40), 5' (19.10.29.6). 



29 Calcite from Union Springs, showing milky crystal of the second 

 generation twinned parallel to c. Forms: a (1120), r (ion), 

 M (4041). 



30 Calcite from Union Springs, showing the prevailing type of 

 scalenohedral twin of the second generation. This combina- 

 tion is drawn with the twinning plane (01 1 2) vertical. Forms : 

 m (1010), 7 ($.8.16.3),^ (7.4.11.3). 



31 Calcite from Howes Cave, showing principal type of crystal. 

 Forms: M (4041)^ (7071), 3> (0.14.14.1), e (0112), q (5167), 

 v (2131), U (10.4.7413), V (62~8i), N (4.i6.~2O~.3). 



32 Calcite from Howes Cave, showing a characteristic penetration 

 twin. 



