135 



to contain liquid' and gas inclusions, and to have been 

 subjected to secondary pressure and granulation along the 

 margins of the grains. The iron pyrites often occurs in well 

 shaped crystals which have been formed subsequently to the 

 crushing. 



The fine dark streaks may have resulted from a shrinkage 

 of the quartz, forming filmy cracks which may have become 

 slip or crushing planes along which the richer gold-bearing 

 solutions were deposited at a later period. 



Brecciated structure of quartz from Mclntyre main vein (natural size). 



The minute dark streaks in the quartz are frequently 

 slickensided, and this character may often be seen in hand 

 specimens, as in those from the Rea or Vipond mines. 



It should be noted that where cracks or fracture planes 

 have been produced in a quartz vein and subsequently filled 

 by minerals from solution, secondary quartz can be dis- 

 tinguished with difficulty, if at all, from the original quartz. 

 Hence it is not always possible to say whether visible gold 

 in such a vein occurs in the original or in secondary quartz. 



