Spodumene and its. Alterations. 327 



Chesterfield, it appeared under low powers to be in large part 

 clear and colorless,' but with its transparency much clouded by 

 a minute granulation (reminding the observer of Olivine) and 

 by abundant cleavage-fissures, some very short and imperfectly 

 parallel, belonging to the imperfect cleavage parallel to the 

 orthodiagonal pyramid, but chiefly in the longer and parallel 

 cleavages of the orthodiagonal and of the prismatic planes. 

 Under a magnifying power of 270 diameters, the granulation is 

 resolved into minute needles of the mineral, closely aggregated i 

 in the direction of the stronger cleavage ; but foreign inclusions 

 are rare, consisting merely of tiny orange-brown films and scales 

 of ochre ; of black opaque scales apparently of Hematite ; and, 

 especially along the wider fissures, of yellowish granules,, scales,, 

 and slender threads of Killinite. Along the fissures, the yellow- 

 ish material was found to be so abundant as to render the vicinity 

 cloudy, even in a thin section of the purest Spodumene; this 

 indicates an incipient alteration into Killinite, etc. Muscovite, 

 also, is found either in crystals or clear lakes with sharp rounded 

 outlines ; but in some cases the Spodumene projects into the 

 Muscovite in long fibres, some of which, associated with many 

 ochreous particles, are also enclosed in the Muscovite. Between 

 the crossed nicols, the mineral polarizes decidedly, with bright 

 sheets of color passing into each other. 



We have next to consider the interesting series of pseudomor- 

 phous minerals which accompany the Spodumene. 



I — Cymatolite after Spodumene. 



An imperfect analysis of this material from Chesterfield was 

 published in February, 1871 (Am. Chem., I, 300), 'and that of 

 Aglaite from Goshen, in May, 1879 (Am. Jour. Sci., Ill, xvii, 

 398). The statement of the occurrence of this mineral at Nor- 

 wich (Dana's Syst. of Min., article "Pihlite") is probably a 

 mistake, Prof. Shepard having informed me that he found 

 Cymatolite only at the Barrus locality in Goshen. Profs. Brush 

 and E. S. Dana have recently called attention to a new occur- 

 rence of the mineral at Fairfield, Conn. (Am. Jour. Sci., Ill, 

 xvi, 34, 1878), where they have found, along with "Spodumene 

 in crystals weighing one to two hundred pounds, Cymatolite, 



