THE SOURCE OF VEIN MATERIALS. 117 



Again since mineral veins appear to have been formed on the earth hy 

 the action of percolating waters, none of the meteorites can be of such vein 

 formation, as has been claimed by M. Mennier, since they show by their com- 

 position that they have not been exposed to or formed in the presence of 

 water; and so far as the present writer is concerned, he sees nothing in their 

 structure supporting such a theory, even if, as Meunier seems to think, these 

 veins were formed by sublimation. 



The finding of many of the metals, in larger or smaller amounts, in 

 meteorites points to a relation between them and terrestrial eruptive rocks. 

 The association of metallic veins with eruptive or metamorphosed rocks, 

 coupled with other characters, indicates that our metals, as concentrated in 

 veins, have generally been derived by aqueous and chemical agencies from 

 eruptive rocks and their debris. This deposition may be direct or indirect, 

 but primarily the starting point is believed to have been the original molten 

 material of the earth.* 



The more common association of metalliferous veins with basic rather 

 than acidic rocks points towards the deeper-seated origin of the former, as 

 has been claimed by many.f 



The occurrence of copper in so many of the meteoric forms has, it seems 

 to the writer, an important bearing on the question of the origin of the 

 native copper of Lake Superior. He holds that it was derived from the 

 associated basaltic rocks as he has set forth in another paper. t 



If copper is an almost constant associate of meteorites, ought it not to 

 naturally be associated with eruptive rocks which are held to be part of the 

 original materials of which the solar system is composed ? The basic 

 rocks are naturally, then, the ones with which the copper should be associ- 

 ated, and it is with basaltic rocks — diabases and melaphyrs — that it is 

 commonly found, as, for instance, on Lake Superior, Bay of Fundy, and in 

 Ne wfo undland . 



The metallic iron in the basalt of Greenland, the native iron found in 

 basalts by Dr. Andrews, that found in gabbros from New Hampshire, by Dr. 

 George W. Hawes, and in gabbros from the west of Scotland, by Mr. J. Y. 

 Buchanan, all serve to connect the meteorites with the terrestrial rocks. § 



* Whitney, Aurif. Gravels, pp. 310, 31]. 



t Whitney, Earthquakes, Volcanoes and Mountain Building, p. 85. 

 t Bull. Mus. Coinp. ZooL, ISSO, vii. 130. 



§ Report Brit. Assoc, 1852, xxii. (Sect.) 34, 35 ; Geikie's Text Book of Geology, 1SS2. p. G t ; Gcol. 

 New Hampshire, 1879, iii. part 4, p. 24. 



