286 



No distinct cleavability could be found. 



Distinctly dichroitic : on {OlOj for vibrations parallel to the c-axis 

 green, for those perpendicular to the former : yellow. On 2^ and '>n 

 the dichroism is only unappreciable. 



On b and m is the angle of extinction about 27°, on /; 44° with 

 respect to the direction of the vertical axis. The plane of the optical 

 axes intersects the edge b -. q on [ 010 | under an angle of about 21°. 



Ammonium-ferri-malonate. 



Pale green, flattened, very lustrous, 

 small crystals. 



Rhomhic-bipyramidal. 

 a:b:c = 0,9407 : 1 : 0,6860. 

 Forms observed -. a=^\ 100 j, predomi- 

 nant, giving sharp reflexes; m = \110\, 

 well-developed and highly lustrous; = 

 [ 111 }, well-developed, and like r = 1 102 j 



{101 j, and 



Fig. 2. 

 Amraoninm-Ferri-Malonate. 



yielding good reflexes ; s 



c = I 001 I 

 reflecting. 



very narrow and badly 



