62 
THE CONSTITUTION OF THE SILICATES 
[BULL. 125. 
in which form it compares better with other analyses. Thus Baumert's 
analysis of axinite from the Hadauthal * gives 
JB0 3 =A10H ,BO 3 =0a 
Al-Si0 4 =) Ca3 + Al-Si 3 8 - k 
\SiO4Z: ) X Si 3 O s E 
and a comparison as follows : 
+ Al Si0 4 ^ 
X SiQ 4 = 
Found. 
Reduced. 
Calculated. 
Si0 2 
40.76 
4.76 
12.47 
2.17 
3.60 
2.84 
30.21 
2.00 
1.22 
40.92 
4.78 
) 13. 91 
r 39. 17 
1.22 
41.32 
4.82 
14.05 
38.57 
1.24 
B.>0 3 
A1 2 3 
Fe^O, 
FeO 
MnO 
CaO 
MaO 
H,0 
100. 03 
100. 00 
100. 00 
Genth's analyses * of the axinite from Franklin, X. J., give similar 
ratios, minus the boron-free molecule required in Baumert's case. 
Approximately they give 
.BO^AIOH B0 3 =A10H .B0 3 =Mn 
4 Al-SiO<= ] Cas + Al-SiQ 4 = , + Al-Si0 4 = , 
\Si0 4 = ) \ Si0 4 = ) \ Si0 4 = 5 Mns 
with rather less than naif the Si0 4 replaced by Si 3 O s . In general, 
when X=Si 3 8 -f-Si0 4 all axinite except that analyzed by Baumert 
gives the general formula 
.B0 3 =B 
Al— X; 
x=i 
\v 
in which K" is partly AlOH, with Oa, Mg, Mn, or Fe. Until further 
evidence is available this expression may be regarded as valid, but it 
represents only the composition of the mineral, and no other relations. 
It is, however, in conformity with the general theory of substitution. 
Other formula, which represent axinite either as metasilicate or as 
orthodisilicate, are possible, but none of them has any advantage over 
the one proposed. 
'Dana's System of Min., Cth ed., p. 529. 
