INTRUSIVE ROCKS OF THE DISTRICT OF MONTREAL. 435 
erystals of brown mica, and a fine grained micaceous variety near 
the summit contains sphene. 
The feldspar in all the specimens of which I have examined appears 
uniform in its character; it is white, rarely greenish, or grayish; 
lustre vitreous inclining to pearly. In its cleavages it resembles 
oligoclase, to which species it is shown to be related by its specific 
gravity and chemical composition ; but I have never seen among its 
erystals the polysynthetic macles so common in triclinic feldspars. 
The specific gravity of a carefully selected fragment was 2.631, of 
another specimen in powder 2.659. The analyses of two different 
specimens gave as follows : 
IX. Xe 
STIG, Ne eRe nt a SU MINN TU LN - 62.05 62.10 
ARETE INS Bis C1 Fale 0D a LA 22.60 
Peraxcydl of anomie Nh ke Musi iieAncie ae “15 
IVT Bre ae Ses SR a CRIS eae el 3.96 3.69 
Ot ashi sey sty rsa st AN PR RA aay a 1.80 
S18 Site a ANAL SINR Ea au a 7.95 
VOLTA Oates at cee Meise ee nue cd 8 
99.91 
Beleil or Rouville Mountain.—The specimens which I have 
examined from this mountain may be described as a micaceous 
diorite. The feldspar, which predominates so far as to give a light 
grey colour to the rock, is in white translucent vitreous cleavable 
grains, with small distinct prisms of black hornblende and scales of 
copper-colored mica. Magnetic iron is also disseminated, and the 
rock resembles the micaceous portion of Yamaska. A portion of 
the feldspar separated by ves, still retained a little mica, and 
gave by analysis : 
XI. 
ISHINGAya Me sete eral ia Naar Nc Le tae ghar) av eake ce ionsiats 58.380 - 
Alumina 
EHIME ash Oy Hes cHIAUEs 40. 2, oh 24.72 
TWO BO Clon BolckoG BO GKISEG COME SER AERA Cine 5.42, 
BIOS ig Le Ss a Fea ee SRE ee 91 
AFPOLAS MY ayedere. ea Ven eh eee awake seca gah hapave Sills. Sieve eghavelatalee 2.74. 
Soda.....0. 5 AE COR COED OAR O IE RCO R ere e Er 6.73 
AViOLA Gil Oy eee Ma cvey Nene oats) at sis ta: sicuieneiauele ie elettie sRelerecers 50 
99.32 
Tt will be seen that this feldspar approaches very closely to that 
from Yamaska numbered VI., and there is much resemblance be- 
tween the two rocks. 
