3 o6 



NA TURE 



| January 25, 1906 



ECONOMIC GEOLOGY IN 

 STATES. 



THE UNITED 



HTHE energy shown by all branches of the United States 

 Geological Survey increases year by year, and it is 

 impossible to overestimate the importance of the results 

 achieved during the twenty-five years of its existence. The 

 prompt return made for the pecuniary support accorded to 

 the survey is best shown by the numerous publications, 

 appearing each year, which are devoted to the development 

 of the mineral resources and to the advancement of 



important engineering projects. The miner is thus taught 

 the practical value of geological work, and mining develop- 

 ment is placed upon a scientific basis. A large number of 

 bulletins have recently been published which, though de- 

 scribing researches of an essentially scientific nature, deal 

 with the economic resources of specified districts. Half 

 a dozen of these bulletins, well illustrating the educational 

 value of the survey's work to those engaged in the mining 

 industry, have been selected for brief notice. Of these the 

 most important is No. 260, " Contributions to Economic 

 Geology, 1004," in which Mr. S. F. 

 Emmons and Mr. C. W. Hayes, the 

 geologists in charge of the sections 

 dealing with ores and non-metallic 

 minerals respectively, bring before the 

 public with all possible speed the 

 economic results arrived at by the 

 survey. The bulletin covers 620 pages, 

 and contains sixty-three contributions aAtff^H 



from thirty-seven members of the 

 survey who have been engaged ,.- , 



throughout the year in economic 

 work. I he production of gold and 'Sry r ' 



silver in the United States in 1904 is ~.*' 



dis, ussed by Mr. W. Lindgren, who 

 has made a novel classification of tin- 

 ores into (1) placer or detrital de- 

 posits, and (2) ores from rock in situ, «■*« 

 further subdivided into quartzose ores, Fig. : 

 copper ores, and lead ores. The per- 



1 entage of the total production derived from the four classes 

 thus established is as follows : — 



Placers Quaruc.se Copper Lead 



Gold 15-2 ... 74.3 ... 50 ... 5-4 



Silver o-i ... 222 ... 34-7 ... 42-9 



A similar calculation of the copper production of the 

 United States, made by Mr. W. H. Weed, shows that of 

 the copper produced 27 per cent, occurs in native ores, 

 6 per cent, in oxide ores, and 67 per cent, in sulphide 

 ores. Mr. L. C. Gratton reports that the tin deposits 



NO. 1891, VOL. 73] 



(dykes of pegmatite carrying cassiterite) of North and 

 South Carolina are probably of considerable economic 

 importance; and Mr. F. L. Hess gives a concise state- 

 ment of what is known with regard to tin deposits through- 

 out the rest of the world. In the Birmingham district, 

 Alabama, an important result of the work of tin- survey 

 has been the extension of the red haematite ore beyond 

 11- supposed southern limit. 



Tin' fuel resources of the United States received 

 more attention last year than at any previous time during 

 the existence of the survey. About 3000 square miles of 

 ic al-bearing territory have been 

 mapped, and work in the oil and 

 gas fields has been continued. The 

 American cement industry formed the 

 subject of an extensive investigation 

 by Mr. E. C. Eckel, and much valu- 

 able information is given regarding 

 the slate, granite, and clay industries. 

 Descriptions are also given of a 

 molybdenite deposit in eastern Maine, 

 and of the vanadium and uranium ore 

 deposits in south-eastern Utah. 



Bulletin No. 255, on the fluorspar 

 deposits of southern Illinois, by Mr. 

 H. Foster Bain, embodies the results 

 obtained in a detailed study of the 

 fluorspar deposits in Pope and Hardin 

 counties, the area covered being at 

 present one of the most important 

 producers of fluorspar in the United 

 States. The deposits were discovered 

 in 1830. but were not mined until 

 1870. The mineral occurs in veins 

 along faulting fissures, and is associ- 

 ated with calcite, galena, and zinc- 

 blende. In 1903 the district produced' 

 11,413 tons of fluorspar, valued at 

 11,5442. The best grade of fluorspar, 

 with less than 1 per cent, of silica, 

 is used in the enamelling, chemical,, 

 lass trades. The second grade is used in open-hearth 



and 



steel making to give fluidity to the slag. About 20,000 tons 

 are used annually in this work. The lowest grade is used 

 in foundry work. 



The zinc and lead deposits of north-western Illinois are 

 dealt with in Bulletin No. 246 by Mr. H. Foster Bain. 

 The region contains large reserves of zinc ore of good 

 quality. The main ore-bearing rock is a thick massive 

 dolomite, known as the galena limestone. Owing to the 

 predominance of solution over disintegration, it presents ora 



ml 



. ■■'■■■■ ■ 



weathered surfaces a very characteristic carious surface 

 (Fig. .)• 



Bulletin No. 249, on limestones of south-western- 

 Pennsylvania, by Mr. F. G. Clapp, is of great economic 

 interest in view of the recent extension of the portland 

 cement industry. It points out promising localities for the 

 erection of cement plants in the coal areas of Pennsylvania. 

 As a rule, these Carboniferous limestones are not suited 

 for building stone, but many of them, when burned, form 

 lime of excellent quality for agricultural, building, and' 

 fluxing purposes. The Vanport limestone, the most per- 



