132 On a Specimen of Native Copper. 



the basaltic rocks, among the debris of which it has been, 

 found, or has it been transported to this position ? " — that is 

 the question to which, in a manner as concise as possible, I 

 wish now to direct your attention. 



We all know that basalt (" bluestone " as it is com- 

 monly called in Victoria) is a natural rock whose chemical 

 composition is comparable to that of the coarser kinds 

 of glass, such as black bottle glass, — that it has been 

 spumed out in a molten state from the interior through the 

 outer crust of the earth, just as the lavas of Vesuvius are 

 seen to be poured out in devastating volumes at the present 

 day. But these basalts present very little of the physical aspect 

 of glass. They have been poured out in a molten condition, 

 gravitating and tilling up the valleys, and forming vast 

 plains of molten vitreous material, which by slow cooling 

 has gradually solidified, and has also undergone a well 

 recognised change, to which glassy matters when slo^vly 

 cooled are known to be subject. Ceasing to be vitreous, the 

 basalt by slow cooling, has become crystalline, and most of the 

 basalts, as we find them, have undergone further changes 

 of decay, due to atmospheric influences, to which all 

 rocks, even the hardest, are more or less subject. This 

 concise explanation concerning the origin of basaltic rocks 

 and their physical condition will, I trust, prepare the 

 way for what I have in the next place to advance ; and it 

 will now be very much to the point if we ask, — whether the 

 occurrence of native metals in the basalts has been in any 

 instance ascertained ? To this question I may at once 

 answer that such occurrences are known, and I may add 

 that the recorded instances are of a most interesting 

 character. 



In the first place, let me mention that it has been jDointed 

 out by Professor Andrews of Belfast (a most reliable 

 authority), that metallic iron is very commonly present, in 

 minute proportions, in such rocks. If iron be placed in a 

 solution of blue vitriol or sulphate of copper, the iron is 

 dissolved and its solution is accompanied by a corresponding 

 precipitation of metallic copper. Dr. Andrews, employing 

 this precipitation of copper as a test of the presence of 

 minute particles of metallic iron ; immersing his powdered 

 rock specimens in the sulphate of copper solutions, 

 examined them under the microscope, and observed little 

 arborescent tufts of metallic copper, often two or three such 

 deposits in the field of the microscope at one time. 



