LEAD AND ZINC. 
Extensive investigations in the principal lead- and zinc-mining dis- 
tricts of the country have been carried on recently by the United 
States Geological Survey. The papers here presented include pre- 
liminary reports covering several of these districts. Other references 
to lead will be found in several papers in the section on gold and sil- 
ver, as all reports on districts in which silver-lead ores were prominent 
were included under the precious metals. 
ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS. 
By George I. Adams. 
INTRODUCTION. 
During the summer of 1002 a party consisting of George I. Adams, of 
the United States Geological Survey, assisted by A. II. Purdue, of the 
University of Arkansas, and Ernest F. Burchard, was engaged in 
the studj 7 of the zinc and lead deposits of northern Arkansas. An 
extensive report on this field is now in preparation. The following 
statement of results and conclusions is made in advance of the final 
publication, which will be accompanied by detailed geologic maps 
and other illustrations. 
POSITION OF THE FIELD. 
The lead and zinc deposits of northern Arkansas are in Marion 
County and adjacent portions of Boone, Baxter, Newton, and 
Searcy counties. Outside of this area there are a few scattered mines, 
notably in Sharp and Lawrence counties, The mining development 
is north of the Boston Mountains, in what is known as the Ozark 
Plateau. The country has a broken surface, as a result of dissection 
by streams, and there are numerous exposures of the mineral-bearing 
horizons in the valley slopes. This has greatly facilitated prospecting 
for the ores. 
HISTORY OF THE FIELD. 
Lead ore was discovered in northern Arkansas by the early explor- 
ers and pioneers, and at first was utilized for rifle bullets. Later it 
attracted considerable attention, and in the fifties was smelted in the 
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