10 



SCIENCE 



[N. S. Vol. XXXIII. No. 836 



eeivable mineralogical aggregate that con- 

 tained ten per cent, of copper would be a 

 very valuable ore, a zinc-bearing aggregate 

 with four or five times as much zinc might 

 be unsalable. 



Suppose we compare them from another 

 standpoint. Copper ores, if at all profitable, 

 are worth about so much per unit of cop- 

 per, that is, so much for each per cent. 

 While there is some variation yet the con- 

 trasts as among three per cent., five per 

 cent, and ten per cent, ores are much the 

 same as the ratio of the per cents to each 

 other. But if we think of a zincblende ore 

 or concentrate of 60 per cent, as the stand- 

 ard of richness, a fifty per cent, ore is not 

 worth five sixths as much, nor a forty per 

 cent, ore two thirds. On the contrary a 

 forty per cent, ore might be entirely unsala- 

 ble. As the zinc decreases other deleterious 

 bases take its place and a worthless mix- 

 ture soon results. Zinc is in many ways 

 the most peculiar of the metals and when 

 we come to deal with its profitable treat- 

 ment analogies with other metals fail. 



In 1907 the United States were the chief 

 producer of zinc among the nations, but, 

 as a rule, Germany leads, followed by this 

 country and Belgium in the order named. 

 In later years our output has varied from 

 26 to 30 per cent, of the total. As a rule 

 Germany is 2-4 per cent, in excess of us 

 and Belgium is 4—5 per cent. less. 



In America, Missouri is the chief source 

 of zinc. Its production from the mines 

 was in 1908, approximately one half the 

 output of the entire United States. New 

 Jersey follows with somewhat over one 

 quarter the total, while all the rest are 

 much smaller. 



The Missouri ores as thus far produced 

 have been obtained from comparatively 

 shallow depths. They extend lengthwise 

 and sometimes laterally to greater dimen- 

 sions than vertically. While it is not be- 



yond the possibilities that lower lying de- 

 posits may be discovered, since zinc ores 

 are found in Arkansas in strata of lower 

 geological position, anticipations of this 

 reserve have not as yet been demonstrated 

 on a large scale. Kansas, Oklahoma and 

 Arkansas, the states neighboring to south- 

 west Missouri, also have some zinc ores, but 

 they are not of great importance; south- 

 western Wisconsin is a very old mining 

 district and has many small mines, which 

 were earlier worked for lead. They have 

 been revived for zinc in later years and 

 are now an appreciable but not great fac- 

 tor. They may develop somewhat more ex- 

 tensively and may last for a goodly series 

 of years, but the mines are relatively small 

 and are wet, so that exploration does not 

 go very far in advance of mining. 



In New Jersey the future is best fore- 

 cast of all. For thirty or forty years there 

 is no occasion of anxiety. Yet thirty or 

 forty years pass quickly and then we must 

 prepare to look for other sources. To make 

 the zinc blende of the Eocky Mountain 

 region available, an increase in price is 

 practically necessary, otherwise the metal 

 can not stand the freight charges. There 

 is zinc ore in the west but to what extent 

 we can not well say. It has been avoided 

 rather than sought in most of our mines. 

 Yet we do note symptoms of attention to it. 

 In Butte, Montana, efforts are being made 

 to concentrate it. Shipments of oxidized 

 ores have been made from New Mexico for 

 some years past. Until recently large 

 amounts of peculiar appearance seem to 

 have been overlooked at Leadville, Colorado. 

 They promise to be an important resource. 

 A government commission has reported 

 upon the occurrence of the metal in British 

 Columbia in the hopes of utilizing the 

 ores. From Mexico, too, we learn of 

 explorations for zinc. Conditions are 

 changing in the case of this metal and 



