A PECULIAR CLEAVAGE STRUCTURE 561 



axis of the approximately elliptical cross-section; (3) parallel to the 

 direction of elongation and to the minor axis of the approximately 

 elliptical cross-section. 



The sections are all alike in showing the' quartz masses to be 

 essentially mosaics of irregularly shaped granular interlocking 

 particles. In a word, the microscopic structure is typically that of 

 crushed and recrystallized quartz. In the first set of thin sections 



Fig. 5. — Micro structure of crushed vein quartz from near EUijay, Ga. The 

 lack of crystalbgraphic boundaries is apparent. 



examined, namely, those cut normal to the direction of elongation of 

 the masses, the grains show dimensional, but not crystallographic 

 parallelism. The longer axes of the grains, as would naturally be 

 supposed, are parallel to the major axis of the elliptical cross-section. 

 This may be and quite likely is due to deformation, but there are no 

 evidences of deformation in sections cut parallel to the direction of 

 elongation of the quartz masses, as might naturally be expected. 

 If due to deformation producible by pressure normal to the direction 

 of flattening, all evidence of internal strain, usually evidenced by 

 wavy extinction, has disappeared, but this might readily be brought 

 about by recrystallization. The perfect interlocking of the grains is 



