Vol. 8, 1922 PETROLOGY: CLARKE AND WASHINGTON 
113 
AVERAGE IGNEOUS ROCKvS, NORTHERN NORTH AMERICA 
\ 
2 
3 
4 
5 
6 
Si02 
60. 19 
0/ . 14 
00 .31 
OD . ly 
;>z . 1 U 
58 . 34 
AI2O3 
15.76 
15.48 
16 . 67 
16 .67 
16 .38 
15.79 
Fe203 
2.87 
0 no 
Z . 1<5 
3 . 0 1 
t (to 
4 . 58 
2.21 
FeO 
3 .67 
A TO 
4 . /Z 
0 Ad. 
J .4o 
4 . 65 
5.83 
3 .99 
MgU 
.3 . Id 
i . DO 
Q 
0 . o\j 
0 . Z/ 
4 . 5/ 
CaO 
4.80 
3.51 
5.05 
5.34 
5.29 
5.66 
NaaO 
3.90 
6.98 
3.85 
4.40 
4.88 
3.54 
K2O 
3.07 
3.25 
2.82 
3.00 
2.65 
3.18 
H2O + 
1.01 
1.12 
0.78 
1.08 
1.09 
1.14 
TiOa 
1.01 
1.50 
0.77 
1.25 
2.20 
0.69 
ZrOz 
0.01 
0.12 
P2O5 
0.26 
0.19 
o'l8 
0'l9 
0'21 
0^33 
MnO 
0.10 
0.21 
0.10 
0.13 
0.17 
0.14 
BaO 
0.04 
0.04 
0.06 
0.11 
Incl. 
0.15 
0^30 
0'l2 
0.26 
0.59 
0.31 
100.00 100.00 100.00 100.00 100.00 100.00 
1. North America, including Greenland, Mexico, Central America, and West Indies 
1709 analyses. 
2. Greenland, including East and West Greenland and Ellesmere Land. 41 analyses. 
3. Alaska. 24 analyses. 
4. Canada, including Alaska, Bast Canada, and British Columbia. 188 analyses. 
5. East Canada, including Ontario, Quebec, Maritime Provinces, and Newfoundland. 
99 analyses. 
6. British Columbia, including Alberta. 60 analyses. 
AVERAGE IGNEOUS ROCKS, MIDDLE AND vSOUTH AMERICA 
1 
2 
3 
4 
5 
6 
Si02 
59.11 
58.70 
61.34 
61.06 
61.85 
54.92 
AI2O3 
16.58 
18.30 
15.20 
15.17 
16.51 
16.29 
Fe203 
2.88 
2.85 
3.03 
2.42 
3.03 
4.05 
FeO 
4.11 
4.20 
3.30 
4.07 
2.28 
3.53 
MgO 
3.07 
3.36 
3.47 
4.65 
2.29 
4.33 
CaO 
5.73 
7.08 
4.88 . 
5.91 
4.55 
5.28 
NasO 
4.10 
3.15 
4.09 
3.29 
4.47 
5.11 
K2O 
2.32 
0.99 
2.69 
1.74 
2.69 
3.57 
H2O 
1.04 
0.79 
1 .05 
0.73 
1.11 
1.55 
Ti02 
0.63 
0.45 
0.56 
0.49 
0.75 
0.87 
P2O5 
0.25 
0.08 
0.11 
0.07 
0.25 
0.11 
MnO 
0.06 
0.02 
0.12 
0.18 
0.22 
0.37 
Incl. 
0.12 
0.03 
0.16 
0.13 
100.00 100.00 
1. Mexico and Central America. 47 
analyses. 
2. West Indies. 82 analyses. 
3. South America. 138 analyses. 
100.00 100.00 100.00 100.00 
4. British Guiana. 45 analyses. 
5. Andes Mountains. 56 analyses. 
6. Eastern Brazil (including Paraguay 
and eastern Argentina). 20 an- 
alyses. 
RARER ELEMENTS IN IGNEOUS ROCKS 
1 
Rubidium 000,x . 00x,x 
Arsenic 000,x . O0x,x 
Molybdenum 000,x .000, Ox 
Tin 000,x .00x,x 
Bromine 000,x .OOx 
Caesium 000,0x . 000,00x 
Scandium 000,0x . 000, 000, 000, xx 
Antimony 000, Ox . 00x,x 
Cadmium 000,0x .OOO.OOx 
Mercury 000,0x .000, OOx 
