320 METALS. 



riflings and disturbances of the beds ; for the beds are tilted 

 at various angles, and the veins show where were the frac- 

 tures of the layers, or the separations and gapings of the 

 tortured strata. The heat appears not to have been of the 

 intensity required for the better crystallization of the more 

 perfectly crystalline schists. The quartz veins could not 

 have been filled from below, by injection. — a view not now 

 accepted for the generality of mineral veins. They must 

 have been filled either laterally or from above. In all such 

 conditions of continued heat beneath an ocean, the hot water 

 would dissolve silica freely within the rocks or from them, 

 (as happens at the Geysirs of Iceland and elsewhere,) so 

 that the region would become one of hot siliceous solutions 

 permeating and overlying the upheaving strata. Thus silica 

 would be free to consolidate or metamorphose the strata, and 

 to fill up all rents or openings, whether they were no thicker 

 than a sheet of paper, or rods in width. The waters would 

 work laterally into these fissures, as this would be the ten. 

 dency of the internal flow or movement, and they would 

 carry mineral material of various kinds with them ; besides, 

 the superficial waters might deposit what mineral matter 

 they contained along with the silica; and at the same time 

 vapors might rise from below along the lines of rents, and 

 be still a third source of rnetallic or mineral material. Be- 

 tween these methods appears to lie the process by which 

 the gold was introduced into the quartz veins, and it remains 

 for further research to ascertain the particular facts in the 

 case. The pyrites formed in the veins is usually auriferous, 

 showing that they were crystallized under the same circum- 

 stances as the depositing of the gold in strings, crystals and 

 grains. Mur.hison has stated, that in the Urals the gold 

 diminishes on descending in a vein ; but this is not yet re- 

 garded as an established truth. The time when the gold 

 veins were formed may differ in different regions. Along 

 our eastern coast it appears to have been after the coal period. 

 An examination of a gold rock for gold is a simple process. 

 The rock is first pounded up fine and sifted ; a certain 

 quantity of the sand thus obtained is washed in a shallow 

 iron pan, and as the gold sinks, the material above is allowed 

 to pass off into some receptacle. The largest part of the 

 gold is thus left in the angle of the pan ; by a repetition of 

 the process a further portion is obtained ; and when the bulk 



