520 



Annals New York Academy of Sciences 



are produced chielly by the action of cosmic rays on iron, silicon, and other sta- 

 ble elements in the meteorite. For example, the 3 neon isotopes are made in 

 nearly equal amounts in this process (Eberhardt and Eberhardt, 1961) whereas 

 in primordial neon (represented by neon in the earth's atmosphere) the ratio 

 Ne^o/Ne^VNe-- is 90.8/0.26/8.9. The elemental ratios differ too, as can be 

 seen in figure 5. The bulk of the primordial noble gases once associated 

 with the matter of the terrestrial planets and the asteroids seems to have been 

 lost at a very early stage in the history of the solar system. It is not very 

 plausible to assume that these gases were first lost from the ordinary chon- 



100 



.10 



c 

 o 

 -o 



c 



■D 

 XI 



< 



"(J 



e 

 (/> 



o 

 o 



■ Carbonaceous Chondrites 

 n Ordinary Chondrites 



Pb 



Pb 



Tl 



Bi 



10 

 10 



In 



Ls_ 



-4 



10'^ 10' "^ 



Observed Abundance (atoms/ 10 atoms Si ) 



Figure 4. Trace element abundances in carbonaceous chontlrites and ordinary chondrites. 

 x\lthough strongly depleted in ordinary chondrites, most of these trace elements occur in 

 carbonaceous chondrites in nearly their "cosmic" abundances. This suggests that carbona- 

 ceous chondrites are more closely related to primordial matter than the ordinary chondrites. 

 [Data were taken from the following sources: Bi, Hg, Pb, and Tl, Reed et al. (1960), and 

 Ehmann and Huizenga (1959); Cd, Schmitt (1961); I and Te, Goles and Anders (1962); In, 

 Schindevvolf and Wahlgren (1960); Sb, Anders (1960).] 



drites, then stored somewhere, and finally incorporated somehow in the car- 

 bonaceous chondrites. 



The spheroidal troilite and magnetite particles found in Orgueil also suggest 

 a high-temperature stage (Fitch et al., 1962). Their chemical identilacation was 

 confirmed by electron microprobe analysis (Smith, 1962). Spheroidal par- 

 ticles might be expected from the condensation of vapors in the liquid field, 

 but in the presence of cosmic proportions of hydrogen, metalUc iron rather 

 than FeS or Fe;j04 would result (Urey, 1952). Such "primary" metal spherules 

 might be transformed to FeS or Fe304 by the action of HoS or HoO at lower 

 temperatures. It is interesting that Sztrokay et al. (1961) have observed 

 spherical, opaque particles in olivine chondrules from the Kaba carbonaceous 

 chondrite. Similar particles are found in chondrules of many ordinary chon- 



