On American Spodumene. _ 871 
ia Il. Mean. Oxygen, Rattle 
Silica, 63:06 6272 6239 3267 3267 804 
Alumina, 28-00 2885 28-42 1328: 1328" -327 
95 ‘. 
ime, 1-43 104 29 
Lithia, 5°67 567, 5-67 3:12 4:06 1 
Soda, 251 251 251 65 
10019 10088 
And that from the ee locality of which also. two analy- 
ses were made, gave 
L Il. ‘Mean. _ Oxygen. - Ratio. 
Silica, . 6286 62°67 62:76 32 6L. 3261 780 
ae: 2883. 2983 29:33 13-75 1375 328 
a ma : ie 
71 6 18) 
Lithia, | 648 648 648 3566 419 1. 
Soda, - 1-76 1-76 1-76 A5 : 
100-49 101-45 
The mean of the ratios calculated from the four analyses is 
L 3 27 : 7-92 or quite nearly 1: 3:8, which gives the general 
ormula 
Rs Si2+341 Si2 
and the special formula 
(0570 Sek 1388 Na+-8097 Li)s Si2-++3Al Si2 
which requires, 
8 atoms of silica, 461848 = pr. ct. 64:14 
3 ‘* alumina, 1925 40 26°76 
2:4291 “ ~~ lithia, 441-27 6-12 
“3999 “ — Roda, 15484 2-15 
a. “ilane, 60°10 ‘83 
| 7200-09 100-00 
This fortiula corresponds quite bis with the analyses, espec- 
ially in the protoxyd bases, the mean of which is almost pre- 
cisely that required by the formula. 
With the specific gravity 3:18 we obtain from the above the 
atomic volume 2264. The B atomic volume (see Mr. Dana’s 
memoir, in this Journal, ix, 220) will be 161:7, and the C atomic 
volume 42:7. The isomorphism of this species with pyroxene 
is pointed out by Mr. Dana on page 120 of this volume.* 
Scene ee 
