78 



Tronsactinns. 



where it will be observed that in each level the foot-wall and hanging- 

 wall seams have been driven on, leaving the centre block intact. 



Shclfl 



Fig. 6.- 



W. 



-Mine-plan, Barewood. 

 X Barren block. 



Thus in the wider portion of the vein the gold has been deposited in two 

 shoots along the walls. The gold-bearing quartz differs from the barren 

 " dog's-tooth " quartz in being seamed and mottled wdth pyritic mullock, 

 and under the microscope is finer in grain. These facts point to a certain 

 amount of replacement along the walls, while the barren block has been 

 formed by simple deposition in an enlarged fissure. 



In places in Nos. 2 and 3 levels there occur pecuhar siliceous concretions 

 (Plate II, 3), cavernous and irregular in form, with a fine chalcedonic banding. 

 They are dark, and coated thickly with very fine pyrites. In appearance 

 they suggest " clinkers " in coal, or fossil forms. 



Associated Minerals. — The dominant sulphide is pyrite, in fine crystals 

 and grains. It is absent in the clear glassy quartz, and thickly distributed 

 in the auriferous quartz. In the No. 3 level there was found within the 

 vein, and near the hanging-wall, a narrow cavity containing a cluster of 

 large stalactites of pyrite. Stibnite, galena, and scheelite occur occasionally. 

 The only one of importance is stibnite, which is becoming common in the 

 deeper levels. 



Habit of the Gold. — The gold is largely free, the assay value of pyrite 

 being low. It is probable, however, that at a greater depth the ore will 

 become refractory. 



