456 Scientific Proceedings, Royal Dublin Society. 



quartz, such as occurs in seams in the clay-slates and mica-schists. 

 Having collected, at hazard, some of these quartz pebbles, they 

 were ground, sampled, and submitted for assay. The return 

 showed a distinct trace of gold less than 2 grains to the ton of 

 20 cwt. 



Of the quartz veins which occur in the slate rocks samples were 

 taken. One from the excavation then in course of execution for 

 the inner dock or basin of Greystones : beds of slate-rock, with 

 veins of quartz and chlorite, forming here the rock-mass ; another 

 from the cutting made on the roadside just south of Crookling 

 Bridge, where the steam tram line curve required the enlarge- 

 ment of the road. The Greystones sample gave a trace of gold ; 

 the Crookling Bridge one nothing. 



A locality better known in the vicinity of Dublin is Ballycorus, 

 on account of the Lead Smelting Works which exist there, as well 

 as the old Lead Mine in the immediate vicinity. Having had 

 occasion to learn that the silver found in the ores of that mine 

 contained gold in an appreciable degree, and assuming that it 

 might be found in the rocks in the vicinity of the mine, I took 

 samples of the mica-schists which occurs quite near in contact 

 with the granite. This rock, not usually considered as a gold- 

 bearing one, being submitted to assay showed traces of the metal ; 

 and, as a further test, mica-schists from the contact at Killiney were 

 also assayed, the result being also traces. Further assays of this 

 rock would be interesting, since its extent would render it worthy 

 of consideration even although the quantity of gold were small — 

 the softness of the rock and consequent ease in working it being 

 capable of in some way compensating for poverty as regards the 

 contained metal. 



This general diffusion of gold through any given stratified 

 rock or rock formation, although not of immediate practical inte- 

 rest, may be of importance at some future period when the 

 methods for the extraction of gold from rocks shall have become 

 so perfected that ores which now present but a mineralogical 

 interest, so far as concerns their yield in gold, may become capable 

 of treatment by these improved processes. 



To this class may fairly be assigned rocks such as the old red 

 sandstone, so extensive in its development in the south of Ireland, 

 and boulders of which are not unfrequent in the drift. As this 



