Intelligence and Miscellaneous Articles. 319 



if we observe any cavities in such gold, we find the sharp edges of 

 crystals, &c. in the same rounded in a similar manner, just as if 

 the whole piece had been subjected to the action of acids, which in 

 reality seems to have been the case. I believe that this is the most 

 natural explanation, because it tells us at the same time to what 

 source we must trace the gold which we find in the veins passing 

 through these formations. 



The greatest difficulty presents itself on inquiring into the nature 

 of the solvent. I do not believe it is very probable that the gold 

 has been carried off as a silicate of gold, or by the action of hydro- 

 chloric acid upon the sulphide. What seems to me most reasonable, 

 is that it was dissolved as terchloride of gold. If we remember that 

 the decomposition of pyrites, one of the most common accessory 

 constituents of diorite, produces sulphuric acid, which, in the 

 presence of the uever-wanting chloride of sodium and a higher 

 oxide of manganese, may liberate small quantities of chlorine, the 

 most powerful solvent of gold, we have at least a very plausible 

 explanation. 



After penetrating the decomposed diorite, the solution of gold, 

 passing down the veins, comes in contact with reducing agents and 

 is reprecipitated again, frequently in crystals or crystalline forms. 

 I shall, below, make a few remarks about the substances which 

 precipitate the gold, in veins as well as in beds. 



An almost positive proof that the gold in the veins of the diorite 

 formation originates from the adjoining rocks, is the fact that the 

 deeper the diorite is decomposed, the deeper the gold is found in 

 the veins. Many of these veins do not contain any gold at 50 

 feet depth ; and I have known veins which were rich near the surface 

 not to contain a trace of gold at 35 feet depth. Very few of 

 these veins (if not on high hills) carry any gold below 120 feet 

 depth. 



The occurrence of gold in beds in the metamorphic olates at great 

 depth can be far more relied upon : Gold Hill, in Rowan Co., N. C, 

 for instance, is over 600 feet deep, and the ore as rich as ever. 

 Although it cannot be denied that the greater portion of the gold 

 in such deposits is as old as the stratum itself in which it occurs, 

 it is certain that inside of such auriferous strata constant changes 

 are going on — gold dissolved and reprecipitated. We could not 

 account for the crystalline structure of most of the gold in such beds, 

 if wc did not presume that the freshly precipitated gold deposits 

 frequently upon that already present. 



The description of a few specimens in my collection may be 

 interesting; for they prove that the gold must have been in 

 solution. 



a. From Whitehall, Spotsylvania Co. Va., — shows gold asso- 

 ciated with tctradymite, limonite, and quartz. Tiie gold is cry- 

 stallized in forms belonging to the rhombohedral system, and showing 

 very distinctly one rhombohcdron, scalcnohedron and basal plan ; 

 it is coating tctradymite, and is evidently a pseudomorph of it. I 



