Quejistcdtitc near Montpclier, lozva. — Kuntsc. 1 1 g 
ON THE OCCURRENCE OF QUENSTEDTITE NEAR 
MONTPELIER, IOWA, 
By De. Otto Kuntze, Iowa City. 
Iron sulphates in their various composition as neutral or 
more or less basic salts or with a various amount of water oc- 
cur very sparingly in nature as minerals and are only met 
with under certain favorable conditions. Without exception 
they are always secondary minerals, i. e., resulting from the 
decomposition (oxidation) of other primary minerals as pyrite. 
marcasite or chalcopyrite. As the oxidation of these minerals 
is a very slow process and the solubility of the resulting sul- 
phates is relatively large, the oxidized portion will be washed 
off by the excess of the percolating water and may be de- 
posited after a more or less long way through the strata at 
any favorable locality in a fissure, mostly in the form of lima- 
nite or other insoluable iron salts, as the often not inconsider- 
able amount of organic matter, contained in the percolating 
water, reduces the very dilute solution; or it may happen that 
other salts are present in solution, which efifect a precipita- 
tion of the iron. In this way the oxidation of the primary 
sulphides remains concealed, to our eyes. 
But there may exist some favorable conditions, producing 
the deposition of the secondary iron sulphates not far away 
from the original primary minerals, (pyrite, marcasite or chal- 
copyrite) ; so that the derivation is highly evident and in- 
structive. Nevertheless such localities are not often met with. 
Not far from Montpelier in Muscatine county, Iowa, is a 
locality, where this mineral-forming process with its products 
and accompanying effects can be observed. Leaving the train 
in Montpelier we follow the stony bed of a small creek. dr\ 
in summer and fall, walking over Devonian limestone, until 
after about one mile and a half we reach a locality, where the 
contact between Devonian limestone and overlying Carbonifer- 
ous sandstone can be observed. The water of the creek has 
washed out and undermined the sandstone, so that the higher 
ledges are somewhat overhanging. At this locality I found 
the lower 3-4 feet of the sandstone incrusted with a yellow dry 
material of the color of natural sulphur or somewhat darker. 
The horizontal extension was about 40 feet and the thickness 
of the incrustation averaging 1-2 inches — altogether there was 
