E. 8. Dana—Chondrodite from the Tilly-Foster Iron Mine. 101 
bly altered, being generally soft enough to be cut with a knife, 
and for this reason a chemical analysis would be of little value. 
Tas_E VIL* 
Chondrodite. Humite. 
C=7-7(010).| A= 0 (001). 
, Cale. 
v. Rath. 
Calculated. | Meas. Calculated. 
J* |1-%| O11 [145° 43” 44” 124° 16’ 16”|124° 16’ 45” 
3 
Jt ripis 035 138 38 38 
= 2/3610 [129 12 57 /135°/135 53 35 [135 52 23 
ae 
R? )7--2| 368 134 28 38 12931129 32 3/129 30 52 
1 
-2| 122 [140 30 10 (121Z/121 45 28 |121 44 23 
“3| 364 1147 6 34 112 25 28 |112 24 37 
2 
R® | 3-2| 362 [152 49 49 |101 [101 39 30 101 39 2 
The color of the crystals is gray to grayish-yellow, and the 
material of which they are composed is never pure, and often 
quite heterogeneous, 
4. On the Optical Properties of Chondrodite. 
In the preceding pages the question of the orthorhombic or 
iheastton of the chondrodite has not been 
the fragment of 
what was originally a specimen of considerable size and beauty ; 
had the d et-red color of ery: 0 nd type, 
and with the exception of the universally present fractures was 
perfectly clear Miele transparent. 
* Table XIV of the Memoir. 
