Spodumene and its Alterations. 345 



The foreign Killinite has only been found in Ireland, on the 

 shores of Killiney Bay, at Killiney and Dalkey, near Dublin, in 

 granite-veins traversing mica-schist, and with Spoduraene, Gar- 

 net and Tourmaline as its associates. The imperfect crystal- 

 lization of the Spodumene at that locality sufficiently accounts 

 for the hesitation with which the theory of the derivation of the 

 Killinite from that mineral has been gradually accepted. This 

 new American occurrence, however, establishes the certainty 

 of that mode of origin. 



Microscopic Character. — On a microscopical examination of a 

 thin section, under low powers, the Killinite of Chesterfield is 

 found to present a slightly greenish-yellow color, with appa- 

 rently the structure of Spodumene. Under higher powers, the 

 Killinite appears to be largely concentrated as a vein-like ma- 

 terial along the stronger cleavage-fissures of the pseudomorph, 

 and exhibits a minute granulation and thready structure, 

 sometimes with comb-like projections on each side along the 

 other cleavage planes of the parent mineral. It is always rich 

 in free Ochre, which substance serves in the thin section as a 

 brownish-yellow coloring material. This, however, is often 

 abundantly separated in nearly opaque reddish-browu flocks at 

 the line of contact between the Cymatolite and Killinite. 



This fact, and the presence of organic matter, suggest that 

 the entire content of iron in this mineral may not exist in 

 chemical combination in the main pseudomorphous substance 

 preseut,jand may not be essential, but may have been in part 

 rejected, during the alteration of the Spodumene, in a ferrous 

 combination with an organic acid. This seems to have been 

 diffused as a greenish coloring material, subsequently oxidized 

 during the artificial preparation of the thin section under ex- 

 amination. If this conclusion be true, a part of the atomic 

 fraction of iron in the calculation of the ratio should have been 

 disregarded; but, aside fr,om replacing it by an equivalent of 

 basic hydrogen, I think the calculation and formula would re- 

 main unaffected. 



When the line of contact between the Killinite and Cymato- 

 lite is examined where it crosses the fibration both of the Killi- 

 nite and of the Cymatolite (i. e., transversely to the axis of the 



