Fis 
ee . es Mica from Abborforss. (Svanberg.) 
20-49 : 15°30 3 3°67 | ee ee 
ist 16-00 : wey: oe 
. Mica from Sala. (The same.) 
enon 6 O01 : 13-65 a ome 
21-00 + 7-00 : 14-00 ¢ 2(R)* Si+R Si. 
9. Pyrophyllite. (Herrmann. ) F 
mn ‘06 : 13-76 33°54 MG Depp ete 
~ id Reed Feed a 3(R) Si+2.Al? Sis. 3 
The insignificant amount of iron in this mineral has been cal- 
culated as protoxyd (=1-16 per cent.), although it is cited as per- 
. oxyd. It may be remarked, that the color of the mineral is 
green, and the analysis indicated a slight excess. 
10. Pinite from Auvergne. (C. Gmelin.) 
29:07 : 13-50 : 3-00 a peek tee dae 
29-00 : 12:88 : 3-22 , 3 (R) Ri +2R° Rie. 
This pinite has therefore the same formula as Herrmann’s pyro- 
phyllite, the preceding mineral. The difference between them 
consists but in this, Ist, that in -pirophyliiie there is only alumina, 
whereas pinite contains peroxyd of iron as well, and 2d, that in the 
former (R)=4Mg, 1-6 Fe, 5-62'H, in the latter =3-76 Mg and 
© Mn, 789 K, 0°39Na, 1-41. Both minerals appear to erystal- 
lize i in the thombic system. -But it does not seem praleblls to 
- me that they should affect precisely similar forms, inasmuch. as ° 
a amount of potash contained in pinite is too considerable 
» fort 
11. Pinite from Penig. (Scott. ) 4 
21-94 : 16°04 : 3-02 wi 
25-00 : 16-67 : 96 ¢ | (R)Si¢2 Al Si. 
This is the formula of the Broadbo mica, In the latter, 
(R)=8-31 K, 1-5 Mn, 3:32; ; in pinite <'11-35 Ky 0-75 Ga and 
, 300 H. Assuming about a third of the iton in the mineral to 
exist in the state of the protoxyd, for which sup - how- 
‘* ever, (excepting, perhaps, t that the analysis indicates an excess of - 
66  Séheerer.on Isomorphism. 
eit sa ula appears to apply to the mica from Miask and 
ek ‘According to v. Kobell’s analysis, their respec- 
e etter ratio is; 21°88 : 9°18 : 10-15 and 21-30 : 9-26 : 11:14. 
ire formula adduced, which is that of garnet, has been before 
applied to these micas, but from not including the water. paone 
i basic aaa the analyses indicated a want of 1: 1 
atomic base 
0-76 per cent.) there is no particular ground ie ‘oem ratio 
0 
es, 
ra 
e 
