142 CONTRIBUTIONS TO MINERALOGY. [bull. 262, 
The combinations observed are shown in the following table: 
Crystal 
No. 
b 
in 
h 
S 
1 
e 
d 
s 
1 
— 
m 
— 
— 
— 
e 
— 
s 
2 
b 
m 
— 
— 
— 
e 
— 
s 
3 
b 
m 
— 
<5 
1 
e 
d 
s 
4 
b 
m 
— 
— 
— 
e 
d 
s 
5 
b 
m 
— 
— 
1 
e 
d 
s 
6 
b 
m 
— 
— 
— 
e 
— 
s 
7 
b 
m 
h 
— 
1 
e 
— 
s 
From all the good measurements, 27 values for p and 24 values for 
q were calculated, the average values being 
p o =.7308 
q o = .7014, 
which agree very closely with those given by Goldschmidt, namely: 
p =.7311 
q o = .7019. 
The values obtained for p and q are as follows: 
Po- 
q - 
Values. 
Measure- 
ments. 
Values. 
Measure- 
ments. 
.7295 
.7297 
.7301 
.7302 
. 7303 
. 7304 
. 7305 
. 7308 
. 7309 
. 7312 
. 7314 
.7316 
.7319 
.7321 
2 
2 
1 
1 
3 
3 
1 
1 
1 
3 
2 
3 
2 
2 
. 6993 
. 70D2 
.7004 
.7005 
.7010 
.7011 
.7014 
.7016 
.7018 
. 7021 
. 7022 
.7026 
.7028 
.7034 
2 
3 
2 
1 
1 
3 
1 
1 
2 
1 
2 
2 
2 
1 
Av., .7308 
27 
Av., .7014 
24 
