game appearance and habit. 
100 E. & Dana—Chondrodite from the Tilly-Foster Iron Mine. 
it was on this account that no attempt was made to make a 
symmetrical drawing of either of them. 
Fig. 22. 
wy 
R? on R? (behind) gave measurements varying, in a series of 
trials, from 78° to 79°: required 79° 4’. 
R* on R* (behind) gave 624°, required 63° 1’. 
F* on R* (behind) gave 72, required 71 173. 
R* on F* (behind) gave 72, required 71 1734. 
These angles on both crystals were identical within the 
allowed error of observation (say 30’). The above are the 
best angles afforded by any of the planes. 
These angles can be referred only to the ist type of humite. 
Decisive proof that this is right is found in the fact that both 
erystals are holohedral, the planes on both sides being identical, 
with the exception of R'. 
The measured angles of Con R®, right and left, were iden- 
tical, though not obtainable with exactness; the measurements 
gave 1524°-154°: this is also true for Con R?, right and left, 
=1403°-1424°. 
The following table includes the most important angles for 
the occurring planes, calculated from the fundamental form of 
the second type on the assumption that the lateral axes are 
equal and the vertical axes have the ratio of 14:15. The 
measured angles are also added, though only approximate ; 0 
the form given they were obtained immediately from the meas- 
urements over the top of the crystals (see above). 
he two crystals described are the only ones which could be 
positively identified. It is very probable, however, that of 
those found others also belong here, as they have rauch the 
crystals are all considera- 
