no. 4 



TEKTITE SPECIMENS — CLARKE AND CARRON 



and elongated bubble cavities are also present, appearing in the photo- 

 micrographs as dark spots. 



Pronounced flow structure, or flow lines, indicative of inhomo- 

 geneity within the glass, appears in both specimens. This structure is 

 revealed by variation in index of refraction resulting presumably from 



B 



Fig. i. — Flow structure diagram prepared from slice of (A) Empire, Ga., tektite, and (B) 



Martha's Vineyard, Mass., tektite. X 3- 



minor compositional differences (pi. 4, A and C). Strain is also 

 present in these glasses and is associated both with the flow structure 

 and inclusions. This strain is evident from the anisotropism that is 

 observed in the sections with plane polarized light, crossed nicols 

 (pi. 4, BandD). 



The flow structure of both specimens here studied in detail conforms 

 quite well to the surface of the specimens. In figure 1 are given flow 

 structure drawings prepared from a projected image of the sections 



