EXDLicn.] ECONOMIC GEOLOGY GOLD. 145 



Gneissic schists compose the country rock. It is distinctly bedded, and 

 its strata, are cut at an acute angle, amounting to about 20° near the vein. 

 A shaft 105 feet in dei)th has been sunk on the vein. At a depth of GO 

 feet a drift has been cut toAvard the west. The width of the vein varies 

 from 1 loot to 4 feet. This is due to undulations in the hanging- wall. 

 Yellow and white quartz composes the gangue, containing free gold 

 either in scales or as "line gold." A mill with 20 stamps crushes the 

 oi-e obtained from this portion of the vein. It is said to run about $15 

 to $20 per ton J but richer ore is expected in some new openings. 



Miner's Delight. 



The middle portion of the vein has received this name. In its position 

 and associations it conforms to the Young America. A shaft 145 feet in 

 depth has been sunk, and some interior develoi)ments have been made. 

 At the time of my visit, buildings and machinery upon the surface had 

 been completed, and it was stated that work would soon be actively 

 resumed. 



Western Extension. 



This is the third portion of the entire vein. It is not worked at pres- 

 ent. Ui)on the vein a shaft has been sunk 100 feet in depth. A 20- 

 stamp mill located on the premises formerly crushed the ore, but now 

 lies idle. The character of the vein and ore remains constant throughout 

 the entire length, 1,000 feet. Occasionally pockets are found that pay 

 very well. To the depths which have at present been reached, the ore is 

 aU more or less decomj^osed, yielding but little fresh pyrite. Some silver 

 enters the bulUon, as 1 was informed. This, too, must be contained in 

 pyrite, as no specific argentiferous mineral is found in the vein. Wiiile 

 working- from the surface, which was a cheap process, large quantities 

 of gold were taken Irom this lode. 



Keviewing briefly the character of the Sweetwater gold-mines, we find 

 that there are both true fissure veins and veins which form an integral 

 portion of the prevailing schists. The great age of the latter iind their 

 physical structure has been the cause of extensive decomx^osition of the 

 ore dowuAvard. Water entering through joints and fissures, together 

 with atmospheric air, have produced a conversion of the pyrite into 

 limonite, thus freeing the gold. From experience obtained throughout 

 this class of veins, we may say that the immediate surface-ores are 

 richer, as a rule, than those found at greater depths. So far as the 

 w^ork in the A'arious mines of this region extends, however, it appears 

 that even at considerable depths the ore contains a sufficiently high per- 

 centage of gold to make it remunerative if worked judiciously. I can 

 see no reason why, under proper management, and with an applica- 

 tion of experience gained elsewhere, many of these mines should not 

 prove to pay upon working. We may assume that the decomposed ores 

 extend to a depth of at least 150 feet. Their extraction and the process 

 of obtaining the gold out of them is both cheap and simple. In case the 

 ore should jirove refractory lower down, methods are at hand to over- 

 come the dilficulty. By crushing, concentrating, and amalgamating the 

 surface ores, good results ought to be obtained. Eventually roasting, or, 

 if the character of the ore should change, smelting may be employed in 

 the process of gaining the precious metal. For a number of years the 

 mines which may now be regarded as most promising can be worked 

 without nuich expense, as the location and class of ore at present elimin- 

 ate nearly altogether the item of transportation. 

 10 GS 



