Scheerer.on Isomorphism. 67 
24:94 : 15-12 ; 3-63 
24-00 : 16-00 : : 4005 . (Sis 44K Si, 
which would give this pinite the same formula as the following 
mineral. The formula first stated sighitadas it, PEE, 8 evi- 
wh dently better. 
Op te 
12. Gigantolite. (Prolte Wachtmeister. 
24:04 ; 16-51: 421 
| 24-00 : 16-00 : 100 ¢ (> Bie +488 
_ The analysis gave an excess of . 56. 
| * 
13. Choraphytive. (Jackson. ae 
7 93-48 : 12-98: 7-75} ah a 
HH . 24-00: 1200:8005  — -(R)*Si+-ALSi. 
i ei amount of potash (1:64 per cent.) was estimated only 
t 
14. Ottrelite. (Damour. ) 
| 22-51 + 11:50 : 731) ie eae OP 
i ee ey sn anil 
| a This and the foregoing ne Foner have the same formula. In 
point of fact, both minerals ‘in the same crystalline form, 
—- 
3-6 H. 
Although the amount of water in ‘the above named varieties of 
mica and micaceous minerals, generally speaking, is but moderate, 
ranging, as it does, between about one and six per cent., yet it, 
In most instances, exercises a corsiderable influence upon the 
formula of these minerals. For the greater part of them con- 
tain such a limited portion of the 1: 1. atomic bases, that their 
quantity of oxygen is materially increased by that of the water, 
even when the amount of the latter does not exceed two per 
e it. as hate Pa we arrive for the most part at improbable 
| formule, neither a of symmetrical relations 
ed with the. formule of 
A" nor when 
»- other minerals ; objections to At § the formula here adduced, as 
a ee e majority of them is concerned, are assuredly 
finllgMNMEEEE Wheat and fuori of magnesium, whieh - 
not her taken Pca aecount. It is a ed 9 a por- 
tion of the srresponding ft 1 atomic S. 
ws : . #y “Piet id 
® 
* ° 
that of a hexagonal prism. -(R) fee Oltrelite =: = 16-72 Fe, 8: 18 Mn, 
5-66, Inchlorophyllite (R) =9'6Mg, 826 Fe, 4-1 Mn, 164K, 
| F cent. If we neglect this amount of water, or endeavor to vn 
& 
