K A auton ND ] 0N A HYDROMICA FROM NEW JERSEY. 
15 
>.) 
Thi. 
as an orthosilicate, the formula 
(KH)r i s(MgFe) 2 4(AlFe)fi I (Si0 4 )H7. 28IT.O. 
It is evident, from these data, that the mica is one which has been 
largely, but not wholly, altered to a vermiculite; the latter term indi- 
cating- a mica in which potassium has been replaced by hydrogen, and 
which has taken up water of crystallization. So far as the analysis 
goes, the condition of the water is uncertain; for it was determined in 
two fractions only, at and above 100°, whereas more fractions are 
needed for accurate diagnosis. Some crystalline water may be retained 
far above 100°, so that the loss above that temperature includes part of 
this fraction plus all the water of constitution. Apart from this uncer- 
tainty the ratios reduce easily in terms of the mica theory to the 
following molecular mixture: 
,Si0 4 == KH, 
3A1— Si0 4 — Al + 6R"' 
^SiOtEEAl 
SiO , = H :i 
-Si0 4 = R" + 5 R'"- 
^SKXeeR 7 " 
,Si0 4 ==R"H 
Si:>, R"H 3 aq. 
Sin, :R"H 
Calculating with the atomic ratios Al : Fe'" : : 2 : 3, and Fe" : Mg : : 3 : 7, 
we have the following comparison between analysis and theory: 
SiO, 
A1 2 3 
Fe 2 3 
FeO 
MgO 
K 2 .--. 
H 2 0, 100° 
H 2 ; above 100' 
lleduced. 
40.24 
10. 34 
24.57 
5.21 
6.78 
2.20 
3.03 
7.63 
100. 00 
a Crystalliuo. 
b Constitutional. 
Calculated. 
40 
55 
10 
51 
21 
71 
5. 
21 
6. 
75 
2. 
27 
al. 
34 
65. 
66 
100. 00 
[n short, the mica consists of muscovitic and phlogopitic molecules in 
the ratio of 9 : 5. 
9R /// 3(8i04)sB / 8, 
5 R'" (Si0 4 ) 3 R" 3 H 3 , 3 aq. 
The mineral is evidently an unusual mica, differing widely from any 
)ther hitherto described. Its very high proportion of ferric oxide is 
ts chief characteristic, and suggests a ferric muscovite as one of the 
mtecedent, unaltered molecules. Such a muscovite is theoretically 
ionceivable, but is not actually known. 
