356 On two Decomposed Varieties of lolite. 



The pinite variety, though generally occurring in indetermi- 

 nate shaped pieces, yet nevertheless is occasionally seen in forms 

 of the same shape and regularity as the iolite, from which, how- 

 ever, it differs essentially in color and hardness. The peculiar 

 tint affected by the pinite is a pale, bluish, chloritic green. Its 

 lustre is pearly, and not particularly shining, except in a few spe- 

 cimens, where the color approaches silver-white. Hardness 2.5. 

 LaminEe neither flexible nor elastic. Common mica frequently 

 pervades the mineral. Specific gravity =2.8, which, however, is 

 a little too high, from the impossibility of disengaging the air from 

 the mineral, when weighed in water. 



The alteration which has taken place in the iolite does not 

 appear to be attributable in all instances to the weathering of the 

 rock ; for we notice perfect specimens of iolite upon the surface of 

 the ledge : and on the other hand, the pinite variety occurs at con- 

 siderable depths from the top of the rock, where it has been laid 

 open by gunpowder. Many individuals are, in part, hard and 

 transparent, while the remaining portions present the aspect of 

 true pinite. It must be mentioned, however, that a new locality 

 of the pinite has of late been discovered, distant about half a mile 

 from that of the iolite, where, judging from the specimens, the 

 engaging rock is less sound, and where no examples of iolite have 

 been noticed. The pinite here is in gigantic crystals, (five or six 

 inches in diameter,) and possessed of unusual regularity. Some 

 of them resemble large hexagonal plates of mica. 



So obvious did it seem that the Haddam pinite is merely a 

 variety of iolite, that I deemed it a superfluous labor to strengthen 

 the opinion by a resort to chemical analysis ; for we have in the 

 present instance, identity of crystalline form as well as of internal 

 structure, similarity in specific gravity, and still farther, both va- 

 rieties entering into one and the same individual. Analogous 

 changes, moreover, are frequent among species whose chemical 

 formulae are not very diverse from iolite ; for example, in the tre- 

 molitic hornblende of Amity, New York, and the sahlitic py- 

 roxene of Canada and St. Lawrence county, N. Y., which often 

 present themselves in a soft serpentine-like state, and this without 

 having suffered any apparent interchange of elements with con- 

 tiguous minerals, and wholly unaltered in chemical composition, 

 with the exception of their hydrous content. The Haddam pinite 

 loses 3.07 per cent, of water on ignition. 



