289 



No distinct cleavabilit}' could be found. 



The crystals are dichroitic; on |100| greenish-yellow for vibrations 

 parallel to the c-axis, for those perpendicular to them: pale green. 

 The plane of the optical axis is |OOJj; the apparent axial angle is 

 small, with the a-axis as first bisectrix. The birefringence is weak. 



Thallo-fehri-malonate. 



Beautiful, pale green, flattened crystals with rectangular borders. 



Ehomhic-bipyramidal. 



a: 6. 0=1:0.9615: J : 0,7050. 



Fig. 5. 

 Thallo-Ferri-Malonate. 



Forms observed-, a = |100|, predominant and very lustrous; 

 r=|102|, large and lustrous; c=|001j, commonly hardly visible, 

 sometimes however well developed and striated parallel \o c : a; 

 m = jllOj, commonly well developed, very lustrous, occasionally 

 narrow, while /> = |120|, which form is ordinarily absent, is much 

 broader in that case than m, but much duller; o^ = \Ui\, well 

 developed; ^=rl21|, also well-developed and lustrous; lo = \221\, 

 much smaller than o, but giving good reflexes; ('j = |122|, very 

 narrow, but exactly measurable; 6 = {010|, very narrow. 



