FT .* sf ‘ 
72 Scheerer on Isomorphism. 
13. Pinguite. (Kersten.) 
‘Its formula, Fe Si+Fe: Si?+15H, may be also thus written, 
(R)? Si+Fe Si, which is the formula of garnet ‘and likewise of | 
the mica from ma Monroe and. Karosulik. 
14. 
According to Lawigs and Wackenroder’s analyses of the bole es 
from Ellinghausen, Cap de Prudelles, and Sasebihl, these mine- 
rals have the formula, R? Si?-+9H, which may be also written, 
see eee 
(R)? Si+2R Si.. This formula agrees essentially with that of 
pyrargillite (which see), and with that of the other minerals there 
cited. In bole however, (R) consists almost entirely of water, 
(24 per cent.,) with minute quantities of magnesia and lime. 
15. Iron lithomarge. (Schiiler.) 
21°64 : 14-65 : 6°55 BN gets Ae 
21:00 : 14-00 : 7-00 : (R)? Si+2R Si, 
formula of the preceding mineral, and others referred to above. 
R= 14-20 H, 3-04 Ca, 2:55 Mg, 1:51 Mn, 0:93 K. 7 
16. Halloylite, from La Vouth and Thiviers. (Dufrénoy.) 
(1.) os la Vouth, 21:12 : 15°72.: 7-11 
(2.) From Thiviers, 22°39 3 15°16 ¢ 7:27. 
_ Mean of the two analyses: 
21°76 ; 15-44 ; 7-19 ee ee 
22-00 : 14-67 : 7:33 , (R)*S1-F eR Si, 
formula of the preceding mineral. In the La Vouth halloylite, 
(R) consists entirely of water (24:83), but in that from oo 
of 22:30 Hand 1-70 Mg. 
17. Mountain Soap, from Thuringia. ( Bucholz. ) 
“mf 22-86 : 14:63 : 6-212 
99:00 : 14-67 : 7:33 (R)°Si+2R Si, : 
formula of the. preceding mineral. There are also altogether, 
ae ae of aa and eal seven di: erent ee 
Thive, Po iene ep from Thuringia ‘The et 
isomorphous naturé of (R) and (8), ‘and the different grades of 
crystalline development, appear to f orm. the leading ‘ES 
isting between’ these minerals. “and meionite can- 
not serene: b be» held to be icine ieee with the other minerals of 
: a in them (R) consists essentially of lime. 
