H>4 0. .1. Derby— Notable Brazilian Diamond. 



according to bis description had everywhere a chagrinS >ur- 

 face, Dufrenoy thought that evidence of adhesion to a matrix 

 was to be found on a part of the flat face, hut in view of the 

 present stone this explanation is evidently inapplicable. 

 Equally inapplicable seems to he the explanation of such 

 features as the pit shown in tig. 2 (three such are reported on 

 the Star of the South) as due to the imprint of smaller 

 diamonds which have fallen away. It is for crystallographers 

 to say if the hypothesis of hemimorphism above suggested is 

 admissible or not to such dome-shaped diamonds as are here 

 discussed and perhaps also to the great Jagersfontein and Cul- 

 linan stones as well. 



Servigo Geologico e Mineralogico de Brasil, 

 Rio de Jaueiro, May 20, 1911. 



