38 
IOWA ACADEMY OF SCIENCES. 
“chunk mineral,” as it is called. It is filled with numerous 
cavities often lined with crystals of lead carbonate or cerussite, 
formed by the alteration of the sulphide. The ore is of excel- 
lent quality, one sample showing 80.55 per cent of lead. 
Up to the month of April of this year the production had 
reached 400,000 pounds, with excellent prospects for the future. 
There is another locality in Allamakee county where lead 
was formerly mined in the Oneota limestone, and a brief 
description of the mines will, perhaps, be in place in this con- 
nection. The diggings were on Mineral Creek (Tp. 99 N., R. 
VI. W., Sec. 13) about two and a half miles south of where it 
empties into the Oneota river. Near the junction of the two 
streams a small town. New Galena, sprang up, and during the 
year of 1856-57, was the scene of considerable activity. 
The mines were in the upper part of the Oneota formation, 
not far from its juncture with the Saint Peter sandstone. 
Mineral Creek has cut its valley through this sandstone and 
well down into the underlying limestone, which here has a 
thickness of something over 100 feet. This latter rock shows 
evidence of considerable disturbance, being more or less brecci- 
ated, and re-cemented by siliceous material. It is full of cherty 
or flinty matter, and is very impure. 
The mines were on a hillside and were worked by means of 
short drifts. Instead of being in crevices the ore occured 
scattered through the limestone, necessitating considerable 
blasting for its removal. None of the drifts extended more 
than 40 or 50 feet from the surface, as the mineral bearing rock 
did not reach a greater distance. 
To separate the mineral great heaps were constructed with 
wood intermingled with rock. These piles were set on fire, and 
the heat was not sufficient to melt the Galena, but only cracked 
the rock into small pieces. Then this v/as washed and the 
mineral was separated. The latter was smelted in a furnace 
located at the mouth of Mineral Creek. During the two years 
that the mines were in operation 63 pigs were turned out, and 
this trifling return represents almost the entire product of the 
district. 
When the locality was visited early in the present year, some 
prospecting was in progress, but with little chance of success. 
Float lead is found quite abundantly in the county, and the 
Oneota contains more or less of this mineral, but it is doubtful 
whether as a rule the ore occurs in well defined crevices, and 
in amount sufficient to make its mining profitable. 
