= * m 4 * ; 
aS * P ‘ * *% 
118 a Iniellige sence. 
ere Bi AL Pe Ge Me it : 
- Birionite, 43°69 44:69 —— 898 O75 0°98 0:82 5-60=100:41, Eri 
: ——— @ 8 —- 434-069 maceprpeenns i Pas 
3. ~ 45°93 48:23 0°60 353 2-44 —= 10078, Canveth 
a “ (dif. loc.) 45°33 4647 236 trace —— sande Garret 
The following are the oxygen ratios for the analyses : : aaa 
2088 : 2265 = 098 : 1106 : 12 
2 910s 3° 2267. == ae tT Ts: 12 ie 
3. $964: 2288 25 2o87 ce 008 s 147 2: 12 Mee 
ae 4, uate ise Oh ae Sa ee LO + 18 Be | 
» Mean" 098 Y4i49 : 12 
are ratio 1 : 11 : 12 appears therefore to be that authorized by the ? 
ses, As no water was found in the 3d and 4th analyses, the spe- 
be is essentially eohyoge. Including the water found by Erni, the 
ratio becomes 1 : 11: 12 : 3, and the formula Rs Si+11A1 Si+ oft. 
It is still possible that 1 : 12 :,12 will prove to be the true ratio; and 
in that case the ratios for margarite, emerylite, euphyllite, and musco- 
vite, have an obvious simple relation, they being respectively 1: 12:8: 
2:19. 58¢ bees 12812 Bs ih: 
atrass, often yields water. B.B. exfoliates, emits a strong light, 
and in = forceps fuses on the edges. Gives traces of fluorine, but 
none o ia. 
Bocdie associated with tourmaline and corundum at Unionville, Del- _ « 
aware Co., Pennsylvania. The impression of the crystals of tourma- , 
line on the lateral see of the mica, leaves a very smooth, hard 
looking surface. . Also in the same vicinity in es Aaa laminz, or 
scales; this variety afforded the analysis No. 4 abov 
Recapitulation. —The following are the oxygen ratios observed 
amo LR the ss and the formulas correspond ng :— 
ies mically as*much alumina silica, or a larger am i 
ese micas are ie yeas those of the ‘following di division, and brittle or but slightly oo 
pm of 
1. iaaiiarted si 12. : 8§= 1 Sede Tene able * Rs Si2+6Al2 Si : 
2. Emerylite, 2 : 12 : ‘es er a ee R32 Si+3Al2 Si. ree 
8. Euphyllite, 1 : 12(#11): ?R3 Si+-118 Si. 
me Micas having atomically % alumina than silica 
+2125 16 
Muscovite, a. = 1:12 :16 3R,12A1,165i. f 
b. Fuchsite, i 12:16 =1: 8 : 108% | 
c. Abborforss, 23:12:16 =1: 44: 6 R28i+3A158i a 
2, Margarodite, 2212/18 1: 6 9 RSi+eA1 Si. iy 
3. Lepidoli 4° 31973 2 =): § 6 RSi+#Si 7 
2:12:20 = 1: 44+ %4 2RSi+3# Si | 
é 6 2:12:30 =1: 2» 86 sRSi+eh we 
d. 2:12:14 =1: 6: 7 ReB5iteRSI | 
4, Phlogopite, 18:12:30 =1: g: 1g sReSi+28 Si 
5. Biotite, a, 12 2:12:24 =—bt61 2 Rs Sit#Si 
_ 6, Pargas, 8 :12:24 =1: 144: 8 R26i+8Si 
, Chrome, =1: 2: 4 RsBi2+oKSi. 
d. Rosendal, (#12 :12:30 =1: 1: 2 SR2S8i+2R6i 
6. Chamouni, Delesse, (#) 4¢:12: 1931: 23: 4 3R25i+5 
q. , 112116 =1: 8: 4 ——— 
