102 THE CONSTITUTION OF THE SILICATES. [bull. 125. 
Offretite r2Al 3 (Si30 8 ) 3 K 2 H.8H 2 On 
unretlte " LlAl 3 (Si0 4 ) 3 CaH.8H 2 J 
^fLzite: :;:;:::;::::: : : .': :::::;:: : 1 Ai3(Sio 4 ) ( si 3 o 8)2 Na 3 .9H 2 o 
.XHR'" 
R— X=R"' 
\x=R' 2 
I 
Double type R" 
I 
/ X=R', 
R— X=R'" 
Anortbite Al 6 (SiO 4 ) 6 0a 3 
Meionite :. Al 6 (SiO 4 ) 6 Ca 2 .(0aO0a) 
Thomsonite Al 6 (Si0 4 ) 6 Ca 3 .7H 2 
Gismondite Al 6 (Si0 4 ) 6 Ca 3 .12H 2 
Phillipsite Al 6 (SiO 4 ) 3 (Si 3 O 8 ) 3 0a 2 K 2 .14H 2 O 
Levynite Al 6 X 6 0a 3 .15H 2 O 
Heulandite ) . , n . _, „ „„ ^ 
Epistilbite } Al 6 (S l3 O 8 ) 6 0a,16H 2 O 
Stilbite Al 6 (St 3 8 ) 6 Ca 3 .18H 2 
Chabazite , Al 6 (SiO 4 ) 3 (Si 3 O 8 ) 3 0a 3 .18H 2 O 
Also the barium feldspars, aud the barium-strontium zeolites harmo 
tome and brewsterite. X represents the tetrad groups Si0 4 and Si 3 8 
indiscriminately. 
C. Second substitution series. 
TypeR-XEZR^ 
\X"R'" 
Natrolite Al 2 (Si0 4 ) 3 Xa 2 H 4 
Dumortierite Al 2 (Si0 4 ) 3 (A10) 6 
Zunyite Al 2 (Si0 4 ) 3 R / 6 
Chloropal Fe 2 (Si0 4 ) 3 H 6 
Cancrinite Al 2 (Si0 4 ) 3 Na 4 H(AlC0 3 ) 
Microsommite Al 2 (SiO 4 ) 3 0aR' 4 
Prehnite Al 2 (Si0 4 ) 3 Ca 2 H 2 
Arctolite Al 2 (Si0 4 ) 3 CaMgH, 
Biotite Al 2 (Si0 4 ) 3 Mg 2 KH 
Siderophyllite Al 2 (Si0 4 ) 3 Fe 2 KH 
Biotite-vermiculite Al 2 (Si0 4 ) 3 Mg 2 H 2 .3H 2 
Biotite-chlorite Al 2 (Si0 4 ) 3 (MgOH) 4 H 2 
Scolecite Al 2 (SiO 4 ) 3 0aH 4 .H 2 O 
Sodalite Al 2 (SiO t ) 3 Na 4 (AlCl) 
