164 Notes on the Area of Intrusive Rocks at Dargo. 



Fig. 2. (a) Dyke of much decomposed igneous rock. {b 

 and b') Quartz veins with gold, arsenical and iron 

 pyrites, (c) Hornfels. 



Fig. 3. (a) Quartz vein, with gold and pyrites, (b) A narrow 

 clay seam, (c) Hornfels. The portion of country in- 

 cluded between a and b is much mineralised. 



Fig. 4. {a) Quartz vein, with gold and iron pyrites, (b) 

 Decomposed dyke of quartz porphyr. (c) Hornfels. 



Plate II. 



Fig. 1. Section of reef at the Eureka mine, Tucker Creek. 

 {a) Quartz-mica diorite, (b) Quartz vein about 18 

 inches in width, with pyrites and a little gold, (c) 

 Porphyrite dyke. Dip to the east. 



Fig. 2. Section of lode at Budgee Budgee mine, Granite 

 Creek, (a) Quartz-mica diorite. (6) Mineralised band 

 of diorite, carrying copper pyrites, (c) Clay seam, (d) 

 Quartz vein, with gold and pyrites, {e) Quartz-mica 

 diorite. The lode dips north. 



Fig. 3. Ground plan of the reef in the Exhibition mine, 

 showing the manner in which "splices" take place 

 between the main vein and smaller veins of quartz 

 from the northern side, (a, a', a") Quartz veins, with 

 gold, galena, and iron pyrites, (b) Hornfels. (c c') 

 Walls of the lode country. 



Fig. 4. Section of the strata at Stringer's Creek, (a and c) 

 Fine-grained sandstone, (b, d and /) Fine-grained slaty 

 rock, (e) Sandstone, coarser grained than a and b and 

 having much argillaceous material, together with grains 

 of quartz. In this rock are numerous narrow veins of 

 crystallised quartz (g) wdiich do not pass into the beds 

 on either side. In places these veins can be seen to 

 have been filled by quartz crystallisations, commencing 

 at each side and meeting in the middle. Under the 

 microscope a thin slice of this bed shows that a con- 

 siderable silicification has taken place throughout the 

 rock, and that the filling of the transverse veins has in 

 all probability been connected therewith, leaving the 

 slaty beds adjoining but little affected. The slaty 

 cleavage, which has affected the beds b, d, f, has not 

 acted upon e. 



