‘ 
. 
~tte . 
aos eS . = => a . 7 oye « “~ 
“ae Po 3 
. 
ae = a ‘ y 
«> “. : a 
Miticralogy and, Geology. 119 
The nigral Diphanite, rese mbles magarite and leapt, accordin 
to _Breithaupt. It has the ratio 10. og 
Ve have not written a Bike pe the muscovite.» It is evident from 
a survey of the compounds, that there must be some more satisfactor 
mode of exhibiting the .relations of subs stances, than by the formulas 
often made out. They frequently make seeming diversity instead o 
quainted wi e wide variation of formula pape ier 8 on a slight 
The amount of water which. analyses afford varies from 0 to 5 per 
cent.; and as it exists variously or not at all, in micas in which the oxy- 
gen ratio is the sam rere is reason for believing it the result of a par- 
tial alteration of the ‘mica, like that which takes place in iolite. | 
ydrous varieties are pmmonly f more or aoe wanting in trans- 
7 
3. Spodumene, (Dana’s Min., 1850, p 1. 693. \—The annexed figure of 
a crystal of Spodumene, from orwiel Mass., has been made ‘by the 
p 
fj 
He 
s 
- 
- 
o 
7] 
Los | 
- 
+f 
rt) 
+ 
T! 
a=) 
° 
a 
S 
5 
ie) 
S 
oO 
a 
9 
a 
os 
Ss 
dl 
7 
ee 
r 
vertical plane b® on the right and the cor- 
responding one on the left wanting, and also 
with the two planes o” and o! unmated ; 
figured are smooth, oooee f oe ee ina 
direction of the intersections as 
Vertical view are shown in hiiaé 2; the ea 
between o/ and a? has a parallel direction 
with that between a and t?, but that between 2. 
and o” is doubtful. The crystal is a M 
Petes long, 13 inches wide, and 1 inch thic 
color is grayish, with a tinge of pee? 
Besides the usual cleava the orthodiag- 
pyramid a—a direction pointed out on the 
figure by the dotted line on plan ne 
surface of plane M moreover is very ‘finely crossed by lines vip a 
ing to this cleavage direction. The c stal is bisected along its orth 
“pee and on holding one of the halves up to the light it is 
seen to be translucent, and marked throughout with the same lines as 
surface. 
a 
