m 



TAB. CL. 



ARSENICUM ferreum. 

 Ironey Arsenic. 



Class 3, Metals. Order 1. Homogeneous. 

 Gen. Arsenic. Spec. Combined with Iron. 



Div. 1. Crystallized. 



Spec. Char. Arsenic in combination with Iron. 

 Syn. Fer arsenical. Haiiy, 4. 56. 



Arsenic pyriteux. Mispickel. Born, 2. 197. 



Native Arsenic alloyed with Iron. Kirw. 2. 256, 



1 his substance much resembles the whitish Iron Pyrites 

 or arsenical Sulphuret of Iron, and seems to have been 

 partly confounded with it by Kirwan; who observes, that 

 " the Marcasite found near Dublin, called Irish Diamonds, 

 is of this species." This latter is however to be most 

 readily distinguished by the crystals being right-angled*, 

 whereas the present is an acutely rhomboidal prism. It is 

 perhaps not unnatural for Irish Pyrites to have a little ar- 

 senic, but not in sufficient quantity to characterize a species. 

 The colour is different in the interior; one being a grayish 

 white, the other yellowish. 



* A small portion of arsenic may be found in th«m, but not sufficient to 

 alter the crystal. 



