CLARKE.] SUMMARY. 105 
Euclase . . : Gl 2 (Si0 4 ) 2 H 2 (A10) 2 
Gadolinite Gl 2 Fe(Si0 4 ) 2 (YO) 2 
g£2t;: :::::::::::: :::::':::::::|rww 
Dioptase n.0uH 2 SiO 4 
Karyopilite Mn 3 (Si0 4 ) 3 H 5 (MnOH) 
Villarsite Mg 3 (Si0 4 ) 2 H(MgOH) 
Serpentine Mg 2 (Si0 4 ) 2 H 3 (MgOH) 
Picrosmine Mg,(SiG 3 )(Si0 4 )H 2 
Aphrodite Mg 2 (Si0 4 ) 2 H 4 
Kerolite - Mg(Si0 4 ) 2 H 5 (MgOH) 
Dewey lite - Mg 2 (Si0 4 ) 3 H 6 (MgOH) 2 .2H 2 
Eudidymite 
Epididymite 
HNaGlSi 3 8 
3. Ortho- and tr (silicates of tetrad bases. 
Zircon n.ZrSi0 4 
Thorite n.ThSi0 4 (?) 
Auerbachite Zr 4 (Si0 4 ) 3 (Si 3 8 ) 
Malacone Zr 3 (Si0 4 ) 3 (OH)H 
Eudialyte ZrXsCl.Ca^a, 
Elpidite Zr(Si 3 8 ) 2 (OH) 2 Na 2 H 4 
Catapleiite Zr(Si 3 8 )(OH) 3 Na 3 
Wohlerite Zr(Si0 4 ) 4 E // 5 Na 2 
Yttrialite Th(Si 3 8 ) 4 Fe // 2 (YO) 8 
Astrophyllite Ti(Si0 4 ) 4 Fe" 4 R' 4 
Johnstrupite Ti(SiO 4 ) 4 Ca 4 (0eF 2 )Na 2 H 
Sphene Ca(Si0 4 )(TiO) 
With rosenbuschite, lavenite, and hiortdahlite, allied to wohlerite; 
rinkite and mosandrite, allied to johnstrupite; and keilhauite and 
tscheffkinite, allied to sphene. 
4. The diorthosilicates. 
Barysilite Pb 3 (Si 2 7 ) 
Melanotekite Pb 2 (Si 2 7 )(Fe /// 0) 2 
Kentrolite Pb 2 (Si 2 7 )(Mn /// 0) 2 
Ganomalite (Pb0a) 3 (Si 2 O 7 ) 
Okenite — Ca 3 (Si 2 7 ) 3 H 12 
Gyrolite Ca 4 (Si 2 O 7 ) 3 H 10 
Apophyllite Ca 2 (Si 2 7 ) 3 H 12 (CaOH) 2 
Plombierite Ca 6 (Si 2 7 ) 3 H 6 . 9H 2 
Inesite R 6 (Si 2 G 7 ) 3 H 6 . 2H 2 
Bementite Mn 6 (Si 2 7 ) 3 H 6 
Spadaite Mg 5 (Si 2 7 ) 3 H 8 
Saponite (MgOH) 2 H 4 (Si 2 7 ).( ?) 
Iolite Al 6 (Si 2 7 ) 5 Mg 4 (A!OH) 2 
