246 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Geology. 



1. Geology and Ore Deposits of Tintic Mining District, Utah; 

 by Waldemar Lindgren and G. F. Loughlin. U. S. Geol. 

 Survey, Prof. Paper 107, pp. 282, 39 pis., 49 figs. 1919.— The 

 Tintic has been for many years an important silver-lead district 

 and lately has also become prominent as a copper producer. It 

 was first studied by the Geological Survey in 1897 but because 

 of the great amount of underground work done since that time 

 and the discovery of many new facts about its geology it seemed 

 advisable to make a resurvey of the area. The field work for 

 this report was done in the years from 1911 to 1914. 



The Tintic district lies in the East Tintic Mountains in Juab 

 and Utah counties, about 60 miles south of Salt Lake City. The 

 Kange is composed of Paleozoic sedimentary and Tertiary 

 igneous rocks. The sedimentary rocks, which include quartzite 

 and limestone, occur in a series of folds the axes of which have 

 a general northerly trend. The district is extensively faulted. 

 The igneous rocks, which cover the greater part of the area, are 

 mostly effusive but include a few stocks and dikes. They con- 

 sist of rhyolite, monzonite, latite, andesite and small quantities 

 of basalt. The eruption of these rocks took place after the sedi- 

 mentary rocks had been folded, faulted and eroded into topo- 

 graphic forms much like those of to-day. 



The ore deposits of the Tintic district have been formed by 

 replacement and filling along fractures. The ore minerals are 

 enargite and galena with subordinate amounts of pyrite, sphal- 

 erite and tetrahedrite. The chief gangue minerals are barite 

 and quartz. The depositing solutions were warm waters ascend- 

 ing in the monzonite area while this rock was still hot. The ore 

 deposits are to be found both in the igneous and the sedimentary 

 rocks, the latter being the more extensive and important. The 

 Tintic district is remarkable for its low water-level which may 

 lie more than 2000 feet below the surface. The oxidized zone, 

 therefore, penetrates to unusual depths. A long list of sec- 

 ondary minerals, some of them quite uncommon, are to be found 

 in the district. More than 80 different mineral species have 

 been noted in the ores. 



The total value of the mineral products of the district through 

 1916 is estimated as $169,000,000, divided as follows: silver 

 $78,000,000, lead $32,000,000, gold $31,000,000 and copper 

 $25,000,000. w. E. F. 



2. The Genesis of the Ores at Tonapah, Nevada; by E. S. 

 Bastin and F. B. Laney ; U. S. Geol. Survey, Prof. Paper 104, 

 pp. 50, 16 pis., 22 figs. 1918. — The study of polished specimens 

 of the Tonapah ores by modern microscopic methods has re- 



