14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



DISCUSSION 



The physical and chemical properties given here for the glasses from 

 Martha's Vineyard, Mass., and Empire, Ga., show a remarkable and 

 unexpected similarity. The measured physical properties show no 

 significant differences. The pattern of compositional similarity shows 

 variations for only four of the elements detected. This observed simi- 

 larity is a significant observation that requires further examination. 



The chemical data in the tektite literature would not lead one to 

 expect such close similarity of properties for two specimens selected 

 at random from widely separated geographic points. In his compre- 

 hensive paper Barnes (1940) gives bulk chemical analyses taken 

 from the literature for 43 specimens from the three major tektite 

 groups (24 indochinites, 10 moldavites, 9 australites) . No two of them 

 suggest agreement comparable to that which has been observed for 

 the Martha's Vineyard and Empire, Ga., specimens. These analyses 

 demonstrate that considerable natural variation of chemical composi- 

 tion exists within the same group of tektites. Larger variations are 

 observed from one tektite group to another. Barnes also points out 

 that compositional variations, as indicated by index of refraction 

 measurements, are observed for different portions of the same 

 specimen. 



The explanation of this observed similarity would seem to lie in 

 one of two areas. The first possibility is that our understanding of 

 tektite specimens and their occurrence is based on inadequate and 

 fragmentary data, so that the observed coincidence is actually an event 

 of reasonable probability. The second possibility, and one that should 

 not be too casually dismissed, is that we are dealing with artificial 

 materials of related origin. Regardless of which explanation per- 

 tains, it is obvious that this problem requires further detailed study. 



There is little room for doubt that the major tektite groups, such 

 as australites, indochinites, and moldavites, are geologic occurrences, 

 the results of natural processes. Georgia tektites have been placed 

 in the tektite category largely on the basis of analogy, as these glass 

 objects have similar chemical and physical properties to known tek- 

 tites. However, the total number of specimens that have been found 

 in Georgia is very small in comparison to the large number that have 

 been found for the major groups. Weights of specimens are not 

 available, but certainly the total for all the 12 reported Georgia finds 

 (Bruce, 1959) must be only some fraction of a pound. Detailed ob- 

 servations relating these few specimens to their geologic environment 

 have not been recorded and seem not to have been made. The situa- 



