and its Contact Phenomena. 29 
The effect of the contact becomes much more striking when 
the percentages of the constituent minerals are calculated from 
the analyses. This was done in the first two analyses as fol- 
lows. The titanium dioxide was first reckoned into titanic 
iron, and the iron sesquioxide calculated into magnetite, since 
the magnet attracts black particles from the powder. The 
remaining iron protoxide, with the manganese oxide, and the 
magnesia were then calculated into a chlorite of the formula of 
ripidolite (Mg, Al,Si,0,,+4H,O). Then if the remainder of 
the alumina is calculated into muscovite (K,H), Al,Si,O,), 
in 
and quartz, as shown by the microscope, hence in the last 
analysis, after calculating the amount of titanic iron and mag- 
netite, the remaining bases were calculated as forming a tour- 
m R,SiO; i f 
n R,Si0s. In accordance with this the 
ap Si 5 
composition of the tourmaline is as follows: 
SiO. Al,O; FeO MnO CaO MgO K.O Na.O H.O BO; Fl 
35°65 36°66 8:03 26 “79 3°72 1:22 3833 285 645 ‘64 = 100 
maline of the formula 
toot or two wide, plays elsewhere. This zone I call the 
mixed zone. At a short distance below the summit it becomes 
a very sharply defined band three feet wide, and consists of 
fragments of various kinds of schist, and angular fragments of 
