288 ORES IN DOLERITE 



been discovered in Mount Ayliff, East Griqualand, near 

 the contact of dolerite l and shales, while similarly 

 occurring impregnations of copper minerals have been 

 found in Cathcart, Queenstown, and a few other locali- 

 ties. Small amounts of galena occur in very narrow 

 veins in the Koggeveld sheets. Prehnite is not uncom- 

 mon in cavities and joints in the dolerites and sometimes 

 carries a trace of gold. At Bekker's Kloof near Cradock 

 there is a vein containing copper pyrites carrying several 

 pennyweights of gold to the ton. 



1 The rock contains a rhombic pyroxene and can therefore be termed 

 norite. 



