CHAPTEE VIII. 
SUMMARY. 
The formula developed in the body of this memoir are so varied and 
so interlinked, one with another, that a summary of them in concise 
form seems to be desirable. I accordingly append such a summary, 
with occasional notes intended to make the subject, if possible, more 
clear. 
1. Ortho- and trisilicates of triad banes. 
A. Normal salts. 
Xenolite Al 4 (Si0 4 ) 3 (?) 
Samoite Al 4 (SiO 4 ) 3 .10H 2 O( ?) 
Cimolite Al 4 (Si 3 8 ) 3 .6H 2 0(?) 
Anthosiderite Fe 4 (Si 3 8 ) 3 .2H 2 0(?) 
Pseudobrookite Fe 4 (Ti0 4 ) 3 
Eulytite } 
Agricolite \ Bl ^ l0 *h 
Of these species the last three are definitely established, but the 
others are more or less uncertain. 
B. First substitution series. 
/X=R' 3 
Type K— X=R'" 
VvzR'" 
Eucryptite Al 3 (Si0 4 ) 3 Li 3 
Xephelite Al 3 (Si0 4 ) 3 Xa 3 
Kaliophilite Al 3 (Si0 4 ) 3 K 3 
Kryptotile Al 3 (Si0 4 ) 3 H 3 ( ?) 
Albite Al 3 (Si 3 8 ) 3 Xa 3 
Orthoclase Al 3 (Si 3 8 ) 3 K 3 
Paragonite Al 3 (Si0 4 ) 3 XaH 2 
Muscovite Al 3 (Si0 4 ) 3 KH 2 
Andalusite ) , n ,„ 
SUlimanite } Al 3 (Si0 4 ) 3 (A10) 3 
Topaz Al 3 (Si0 4 ) 3 (AlF 2 ) 3 
Kornerupine* Al 3 (Si0 4 ) 3 (A10 2 Mg) 3 
Rectorite Al 3 (Si0 4 ) 3 H 3 .2H 2 0(?) 
Hydronephelite Al 3 (Si0 4 ) 3 Xa 2 H.3H 2 
'Doubtful. Compare with formulas given for pyroxenes and amphiboles. 
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