530 OKIGIN OF GOLD. 



public. Till then we rest in the conclusions to which our more limited field has conducted 

 us. 



ORIGIN OF GOLD. 



Since gold occurs chiefly in talcose schist in Vermont, as in other parts of the world, 

 this is the place to say something of its origin. It is a question which every reflecting 

 man is ready to put to the geologist, but not one of the easiest to answer, nor one on which 

 there is perfect agreement. The inquiry as to its localities and amount in Vermont, will 

 be met by the Report on Economical Geology. But the theories as to its origin demand 

 attention under the scientific head. 



" Gold occurs in lodes (veins) of quartz, brown hematite and iron pyrites; in clay slate, 

 graywacke, mica slate, hornblende slate; in granite, gneiss, syenite, quartzose porphyry, 

 gabbro, diorite, diabase, aphanite, serpentine, and dolomite ; in the gravel and sand of 

 rivers as nuggets, laminae and dust, generally accompanied by quartz, brown hematite, 

 zircon, magnetic oxyd of iron, iserine, spinel, &c." (Bischof.) 



But though this metal has been found more or less in so many rocks, its principal 

 deposit all over the world is in metamorphosed Silurian, Devonian and carboniferous schists, 

 frequently near their junction with eruptive rocks. Altered Silurian rocks are probably 

 its most frequent position, and the quartz veins, traversing these, its immediate matrix. 

 It is such veins traversing talcose schist that affords gold in the Ural Mountains, Aus- 

 tralia, California, and along the Appalachian Mountains of the United States. Gold 

 occurs, also, in the schist itself, and this not unfrequently becomes decided mica schist. 



It is in the talcose schist chiefly that gold is found in Vermont, and by looking at the 

 space covered by that rock on our Map, we can see the probable limits of any profitable 

 explorations of that metal. It is found, however, in some quantity in gneiss, as at 

 Bridgewater, and on Danby Mountain in the region of talcoid slate and limestone. But 

 generally it is in superficial deposits of coarse sand, gravel and bowlders, lying above 

 the talcose schist formation, that any quantity worth working has been found. In 

 Bridgewater, indeed, a vein, or more probably a bed of quartz in gneiss, has been 

 explored, and a small quantity of gold obtained from it : but not enough to yield any 

 profits. And with few exceptions, this has been found to be the case the Avorld over. 

 In all the Ural Mountains, only one quartz vein has been found rich enough to repay the 

 expense of working, though it is thought, and often asserted, that the case is different in 

 California. But for the most part nature has collected the gold in the clay, sand and 

 gravel of the low grounds, and there it is most easily obtained. 



We are not certain of the existence of gold in the rocks, in any other than a metallic 

 state. It occurs, however, in minute quantities in galena, and in copper and iron pyrites, 

 and it is probable that it exists in them in the state of sulphides. In such a case, the 

 oxydation of the sulphide would eliminate the gold, and water would remove it and 

 throw it into the form of, alluvial deposits : but to this point we shall recur again. 



But little gold has been found in the secondary and tertiary rocks, although the 

 materials of which they are composed were obtained by erosion of the palaeozoic or met- 

 amorphic rocks. Hence Sir Roderick Murchison infers that the gold could not have been 

 introduced into the palaeozoic schists, till after the deposition of the secondary and tertiary 



