MINING. 275 



^inds of rock, are usually richer than those which have the 

 same kind of rock on both sides. Thus it is said that the richest 

 veins of auriferous quartz in California, have been discovered 

 at the intersection of trap and serpentine, and the richest places 

 in veins are where they cross from one kind of bed-rock 

 into another. The richest part of a lode of auriferous quartz 

 is almost invariably on the lower side of the vein, near the 

 foot-wall. All these are facts to be remembered by the pro- 

 spector as a guide, and an assistance to him in his search for 

 a rich gold-bearing vein. If the lode is covered with earthy 

 matter, he may sometimes trace its course by the difference in 

 the color of the dirt and stones over it from that elsewhere. 

 When the prospector finds dirt and stones on a vein, evidently 

 disintegrated portions of it, he should wash some of the dirt 

 in a pan, and if he finds no gold, there is a strong presumption 

 that the vein is barren. 



§ 205. Prospecting Quartz Rock. — After finding a gold- 

 bearing vein, the question arises whether it will pay. Great 

 sums are lost in gold-mining countries by injudicious invest- 

 ments in mills and machinery to work the auriferous rock, and 

 persons going into the business should be particularly careful 

 not to commit this great error. The business of quartz min- 

 ing has great profits but also great pecuniary dangers con- 

 nected with it. It is rarely that all the rock of a vein will 

 pay for working. In some lodes, the vein-stone will average 

 one hundred dollars to the ton, for all the stone found in a cer- 

 tain part of the lode, but beyond that the rock may be poor 

 or worthless. Picked specimens may be worth several thou- 

 sand dollars to the ton, but perhaps not more than a ton of 

 such specimens has been obtained in the best lode ever opened 

 in the state. The most profitable lodes are those which have 

 a large supply of rock, easily to be obtained, and all of it yielding 

 something above the cost of working. The common method 

 of ascertaining whether rock will pay, is to pulverize a little of 

 it and wash it in a horn spoon. In taking out the quartz rock 

 in large lodes, it is important to take out only that Avhich wiU 



