EF. 8S. Dana—Chondrodite from the Tiliy- Foster Iron Mine. 98 
the following which fall in the old vertical or horizontal zones, 
and many others to be described later; 0 (7-2 = 210), 7? (27= 
021), 27 (4-7=047), 2 =(2-1=025), e* (2-4=205), r* (8-2=489). Of 
these the most interesting is the prism 7-2, as hitherto no verti- 
cal prism has been found on either the 2d or 8d types. 
Hemihedrism.—The crystals of chondrodite should show an 
entire correspondence to humite in hemihedral characters. 
Taking the same position for the crystals as vom Rath, r? and 
r* appear uniformly in the positive (or upper) quadrants, r' 
and r® always in the negative (or lower) and n? is both + and 
—, but where occurring alone is generally negative ; n! is gen- 
erally, and m? is always, negative. f the brachydomes it 
may be said that they are often holohedral, but this is not 
always the case. The various figures on the two plates will 
show the true relation better than words. It is to be said, 
however, that when the brachydomes are + they are still distin- 
guished from each other physically. Thus the + series may 
largely developed and rough, destitute of any semblance to 
— , When the negative series is as lustrous as the pyramidal. 
planes. 
_ Habit,—With regard to the general habit of the crystals, it is 
interesting to note the wide variation which is shown. Fig- 
ures 1, 2, 6, 9, 10 are intended to give some idea of the crys- 
tals might be mentioned. One crystal of a very prismatic 
esence of minute planes.—The most remarkable feature of 
the mineral from this locality is the multitude of minute planes 
which modify many of the solid angles. One single case will 
€ discussed in detail, as the planes admitted of more than 
subject, A horizontal projection of a portion of the crystal is 
shown in fig. 14. The crystal itself was small, and unfortun- 
ately so imbedded in dolomite that it was for the most part rough 
