18 
MUSEUM BULLETIN NO. 30. 
1 
2 
3 
Si0 2 . 
47-58 
45*42 
77*86 
AI 2 O 3 
18-03 
10*64 
11*96 
FeaOa . . ....... . . . . .... 
MO 
3*03 
0*21 
FeO. 
3*34 
10*22 
0*32 
(Fe) 
(3*37) 
(10*08) 
(0*40) 
MgO. 
10*88 
13*82 
0*29 
CaO . 
16*92 
11*84 
1*92 
K 2 0 
0*32 
0*45 
0*31 
NaaO . . . . 
1*04 
2-17 
5-67 
H 2 6 .. 
0*60 
2*20 
0 60 
MntT 
0*06 
0*08 
0*02 
Ti0 2 . 
0 20 
‘ 0*30 
0*25 
P 2 O 5 
0*01 
0*01 
0 04 
C0 2 
0*03 
100*08 
100*21 
99*45 
1. Fresh, rather fine-grained olivine gabbro, containing approximately 
5 per cent of olivine, the remainder pyroxene and feldspar in about equal 
proportions. 
2. Hornblendite, from one of the large zones, observed under the micros- 
cope to be composed almost wholly of fresh, granulated hornblende. 
3. Aplite, a fresh specimen of medium composition, containing perhaps 
somewhat more than the average of ferromagnesian mineral. 
Rock Alteration. 
* - * 
The gabbros are on the whole only slightly altered. They 
have, however, been affected, subsequent to consolidation, by 
shearing movements, juvenile solutions, and meteoric solutions. 
As regards the first, regional stresses have caused a certain 
amount of faulting, with production of wdde shear zones. Granu- 
lation of the gabbro and its partial conversion into schist 
undoubtedly took place along these zones, but these effects have 
been obscured by the action of the hornblendite-forming solu- 
tions, which flowed through the fault channels depositing horn- 
blendite. A later faulting has sheared the hornblendite with 
formation of much chlorite. The second type of alterative agent, 
the juvenile solutions, tended to convert the rock into aplite and 
hornblendite. As a result, swarms of veinlets of these two types 
penetrate the mass. 
