356 On two Decomposed Varieties of Iolite. 
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, 
Laminz 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. [t 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 4 
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 ve 
rieties entering into one and the same individual. Analogous 
changes, moreover, are frequent among species whose chemical 
formule 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. — 
