Haworte. | Geology of Lead and Zine Ores. 55 
Winslow” has treated this subject so well that a quotation 
from him is here made: 
“The Age ofthe Enclosing Rocks of the Geological Distribution .— 
Deposits of lead and zinc ores occur in rocks of all ages, from 
the Archean to the Tertiary. Those of most importance as 
sources of lead and zine are, however, more abundant and 
- more extensive in Paleozoic and Mesozoic rocks than in 
Algonkian or Archeean. The series containing the largest 
and most noted deposits are the Silurian, Lower Carboniferous 
and Triassic. Examples of all are contained in the descrip- 
tions of the next two chapters. To illustrate these facts a 
little more prominently, however, we give the following list 
showing the distribution of the more prominent deposits. 
““Denosits in Archean or Pre-Paleozoic Rocks.— Ores of lead 
and zinc in large quantities in these rocks are not common in 
America. Those of Franklin furnace, New Jersey, are per- 
haps in Archean formations, and some of the deposits of the 
Kootenay district of Canadaare inthe Laurentian. In Europe 
are to be cited lodes of the Erzgebirge and northeastern 
Hungary; portions of the deposits of Les Malines, of Pontgi- 
baud, of Correze and Aveyron, of Huelgoat and Poullaouen in 
France, and others in Corsica; also some of the less important 
ones of Sardinia and of Linares in Spain. The Ammeberg 
zine deposits of Sweden are in Laurentian rocks, and the lead 
deposits of Sala in Primitive magnesian limestones. The 
silver-lead ores of Broken Hill in New South Wales are in 
Primitive gneiss and other rocks. 
“* Deposits in Cambrian or Silurian Rocks.—In America, the 
lead and zinc deposits of Wisconsin, lowa and of central and 
southeastern Missouri are in Lower Silurian limestone; 
those of Eureka, Nevada, are partly in the Cambrian and 
Silurian ; those in Kootenay, Canada, are largely in Cambro- 
Silurian ; those of Wythe county, Virginia, are also in the 
Cambro-Silurian ; those of Saucon Valley, Pennsylvania, in 
the Lower Silurian, and others in the Upper Silurian ; prob- 
ably the Franklin furnace ores of New Jersey are in Cambrian 
rocks. In Kurope the Przibram lodes are in the Silurian ; 
the lodes of Shropshire and adjacent counties of western 
26. Winslow, Arthur: Mo. Geol. Surv. Rep., vol. VI, p. 46. Jefferson City, 1894. 
