UIU.EBRA 
NDPENFIKLI) 
ND "1 
CLI>. J 
ADDITIONS TO THE ALUNITK-J AKOSITE GROUP. 
37 
JAIIOSITF, AND ATjUNITE. 
As may be seen from the published analyses of these minerals, the 
kali metal they contain is almost always potassium, though sodium is 
t times present. The formulas assigned to the two minerals are there- 
ore K 2 0+3Fe 2 O s +4S0 3 +6H 2 and K 2 + 3A1 2 3 -f 4S0 3 + 6H 2 0, 
rhich may be variously expressed, as will be indicated later. 
A mineral corresponding to natrojarosite of this article, though con- 
lining a little potash, has been described by W. P. Headden a from the 
Juxton mine, Lawrence County, S. Dak. The crystals are described 
I scales, consisting of a combination of base and rhombohedron. 
'he material analyzed was evidently somewhat impure, as quartz 
nd some As 2 5 are reported. As the As 2 5 evidently does not 
elong to jarosite, the assumption may be made that some scorodite, 
'eAs0 4 .2H 2 0, is present, and the results of Headden's analysis may 
ben be interpreted as follows: 
e 2 3 . 
a 2 . 
2 0.. 
aO .. 
v.. 
2 o.- 
rartz 
Original 
analysis. 
46.27 
4.35 
1.47 
.39 
28.46 
10.55 
2.36 
6.10 
99. 95 
Scorodite 
and quartz. 
1.60 
.72 
2. 36 
6.10 
10.78 
Natrojarosite. 
44. 67 or 50. 10 
4. 35 oi 4. 86 
1.47 or 1.65 
. 39 or . 44 
28. 46 or 31.93 
9. 83 or 11.02 
Ratio. 
89. 17 or 100. 00 
3. 13 
1.04 
4.00 
6.13 
Thus, assuming the presence of 4.68 per cent of scorodite and 6.10 
quartz, and deducting them, the remainder agrees very closely with 
itrojarosite, giving a good ratio, very near 3:1:4:6. 
Alunite containing considerable soda has been described by Whit- 
tn Cross 6 from Rosita Hills, Colorado, and by E. H. Hurlburt' from 
>d Mountain, Colorado, and analyses of both minerals show about 
ual percentages of K 2 and Na 2 0, or a molecular ratio of 
2 0:Na 2 = 4: 7. The occurrence, therefore, of sodium in the jarosite- 
Enite group is in accordance with previous observations, but the 
e is quite different with lead. As far as the present writers are 
s/are, this is the first instance on record where lead has been observed 
ipmorphous with the alkali metals. It is interesting to note that the 
ajinite from Red Mountain, Colorado, occurs as a crystalline powder, 
|e crystals being exactty like those of natrojarosite and plumbojaro- 
, "Am. Jour. Sci., 3d ser., 46, 1893, p. 24; Mbid., 41, 1891, p. 472. elbid., 48, 1894, p. 130. 
