679 



TABLE 735.— VARIATIONS IN THE ISOTOPIC COMPOSITION OF COMMON LEAD* 



Relative isotope abundances 



Source of lead Locality Geological age 



Galena Great Bear Lake, Canada . . . Pre-Cambrian 



Galena Broken Hill, N.S.W Pre-Cambrian 



Cerussite Broken Hill, N.S.W Pre-Cambrian 



Galena Yancey Co., N. C Late pre-Cambrian . 



Galena Nassau, Germany Carboniferous 



Cerussite Eifel, Germany Carboniferous 



Galena I Joplin, Mo Late Carboniferous . 



Galena II Joplin, Mo Late Carboniferous . 



204 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 

 1.000 



Galena Metalline Falls, Wash Late Cretaceous 1.000 



Cerussite Wallace, Idaho Late Cretaceous 1.000 



1.000 



Wulfenite and 

 Vanadinite . . Tucson Mts., Arizona Miocene 1.000 



Galena Saxony, Germany 1.000 



1.000 



206 



15.93 

 16.07 

 15.92 

 15.93 

 18.43 

 18.10 

 18.20 

 21.65 

 21.60 

 21.65 

 19.30 

 15.98 

 16.10 



207 



15.30 

 15.40 

 15.30 

 15.28 

 15.61 

 15.57 

 15.46 

 15.88 

 15.73 

 15.75 

 15.73 

 15.08 

 15.13 



208 



35.3 



35.5 



35.3 



35.2 



38.2 



37.85 



37.7 



40.8 



40.3 



40.45 



39.5 



35.07 



35.45 



18.40 15.53 38.1 

 17.34 15.47 37.45 

 17.38 15.44 37.3 



For reference, see footnote 45, p. 136. 



TABLE 736.— LEAD RATIOS OF SELECTED RADIOACTIVE MINERALS* 



Mineral Locality Geologic age 



Samarskite Glastonbury, Conn Pre-Triassic 



Pitchblende Jachymov, Bohemia Late-Paleozoic . 



Thorite Brevig, Norway Permian (?) 



Kolm Giillhogen, Sweden Latest Cambrian 



Broggerite Karlhus, Raade, Norway Pre-Cambrian . 



Cleveite Aust-agder, Arendal, Norway Pre-Cambrian . 



Uraninite Keystone, S. Dak Pre-Cambrian . 



Uraninite Sinyaya, Pala, Carelia, Russia Pre-Cambrian . 



Age ratio in 



u" years 



270 



220 



230 



400 



900 

 1000 

 1500 

 1850 



For reference, see footnote 45, p. 136. 



TABLE 737.— ANALYSIS OF THORIUM C" (THALLIUM 208) BETA-RAY 



SPECTRUM 2S3 



231 Rutherford, E., Chadwick, J., and Ellis. C. D., Radiation from radioactive substances, Cambridge Univer- 

 sity Press, 1930. 



SMITHSONIAN PHYSICAL TABLES 



