CLARKE.] 
META- AND DIMETASILICATES. 
99 
in it as hydroxyl replacing fluorine. This can be interpreted either as 
a dimetasilicate or as a trisilicate, with the following alternative for- 
mulae: 
E 
Si 2 5 — R— B0 2 || 
R< /Si 3 8x 
>Si 2 5 or r< \r 
K< >Si 3 8 < 
\ S i,0 5 — R-F 0=B/ \R— F 
Its association with feldspar and schefferite rather favors the trisili- 
cate formula, but the two are empirically identical. If we reduce 
Lindstrom's analysis to 100 per cent, after calculating the water 
(ignition) into its equivalent of fluorine, rejecting as impurities the 
traces of A1 2 3 and Fe 2 O s , and consolidating like bases, we get the 
following comparison with theory : 
Si0 2 . 
B 2 3 . 
PbO. 
CuO. 
MnO. 
GIO . 
Na 2 
CaO . 
BaO. 
MgO. 
K 2 . 
AI2O3 
Fe 2 3 
F.... 
CI... 
Ign.. 
Less O. 
Found. 
100. 37 
Reduced. Calculated. 
38.60 
3.63 
25.71 
9.43 
21.32 
38.10 
3.71 
26.22 
9.22 
21.59 
2.26 
2.01 
100.95 
.95 
100. 00 
100. 85 
.85 
100. 00 
In computing, ~R" has been regarded as Ca:Ba:Pb:: 7:6:5 — that is, 
hyalotekite is a mixture of isomorphous calcium, barium, and lead salts 
in the indicated ratio. The agreement between analysis and theory is 
as close as could be reasonably expected. 
There still remain a few natural silicates which are definitely recog- 
nized as species, but which do not fall distinctly into any one of the 
chapters of this work. Their constitution is obscure, and I shall not 
attempt to discuss them. Still, they may properly be recorded at this 
point for the sake of completeness. 
Cuspidine. — A fluosilicate of calcium, supposed to be orthosilicate in 
structure. It may be allied to chondrodite, but it has not yet been com- 
pletely analyzed. 
