340 Spodumene and its Alterations. 



In the Goshen variety of the mineral, Aglaite, the pseudo- 

 morphons material was never formed as an enveloping crust, 

 but entirely in the direction of the axes of the prisms. The 

 density and toughness of the matrix would appear generally to 

 have allowed the commencement of the attack only from the 

 terminations ; and the rapid progress of the alteration in the 

 direction of the axis (as also in less degree along the cores of the 

 Chesterfield prisms) seems to have been caused by the more 

 ready wedging up of the Spodumene in its easiest plane of cleav- 

 age, the orthodiagonal, by the pointed ends of the Cymatolite 

 blades. As fast as produced at the sharp alteration-line (marked 

 in Fig. 2), the minute spicuhe and scales of Cymatolite hardly 

 attained a length of a few hundredths of a millimetre before they 

 were thrust aside in the same plane. The pressure was exerted 

 mainly in that plane; laminae were projected outwardly into the 

 granitic gangue, perhaps somewhat plastic and yielding (result- 

 ing in the present lateral adherence of the altered prisms) ; and 

 the lamina? thus retained the flatness, without crumpling, pecu- 

 liar to Aglaite. 



II — Killinite after Spodumene. 



A second pseudomorphous material of the Pinite family, ap- 

 parently Killinite, was found, frequently but in limited quan- 

 tity at Chesterfield Hollow, and quite rarely in the Huntington 

 vein. It sometimes occupies the entire core of some of the small- 

 est Cymatolite pseudomorphs, in a dark mass, perhaps 1 to 2 

 inches in diameter. But ordinarily it constitutes only an outer 

 layer of the Spodumene core, intermediate between that mineral 

 and the enveloping crust of Cymatolite, in some of the larger 

 crystals : in such cases it is rarely continuous, but usually oc- 

 curs in isolated spots or sheets, presenting often a broken or 

 wavy dark line along the fracture-section of the outer edge of 

 the Spodumene-core. The contiguous portion of the Spodu- 

 mene, though retaining its white color, is also found to show 

 alteration, both by its yield of water, when heated in a closed 

 tube, and by the exhibition under a pocket-lens, of very minute 

 dark films of Killinite in a delicate net-work. 



The purest Killinite presents the following characteristics. 



