280 EESOUKCES OF CALIFORNIA. 



The arastra is a slow instrument, but in some important re- 

 spects it is superior to any other method of working auriferous 

 quartz. It grinds the quartz well, is unsurpassable as an amal- 

 gamator, is very cheap and simple, requires no chemical knowl- 

 edge or peculiar mechanical skill in the work, requires but little 

 power, and very little water — all of them important consider- 

 ations. In many places, the scarcity of water alone is enough 

 to enable the arastra to pay a larger profit than any other 

 method. Again, if a miner finds a rich spot in a lode, he may 

 be doubtful as to the amount of paying rock which he can ob- 

 tain. Such cases very frequently happen in California, and 

 the arastra is just the thing for the case ; for then if the 

 amount of paying rock is small, nothing is lost, whereas the 

 erection of a stamping-mill would cost much time and money, 

 and before it could get into smooth operation the rich rock 

 would be exhausted, and the mill perhaps become worthless. 

 No other simple process of amalgamation is equal to that of 

 the arastra ; and it has on various occasions happened in 

 California, that Mexicans making from fifty to sixty dollars 

 per ton from quartz, have sold out to Americans Avho have 

 erected large mills at great expense, with patent amalgama- 

 tors, and have not been able to get more than ten or fifteen 

 dollars from a ton. The arastra is sometimes used for amalga- 

 mating tailings which have passed through stamping-mills. 



§ 209. Chilean Mill. — The Chilean mill has a circular bed 

 like the arastra, but much smaller, and the quartz is crushed 

 by two lai'ge stone wheels which roll round on tlK'ir edges. 

 In the centre of the bed is an upright post, the top of 

 which serves as a pivot for the axle on which both of the 

 stones revolve. A mule is usually hitched to the end of one 

 of the axles. The methods of managing the rook and anialga- 

 matino- Avith the Chilean mill, are very similar to those of the 

 arastra. The Chile.;n mill, however, is rarely used in Califor- 

 nia ; the arastra being considered far preferable, 



§ 210. Stam2)S. — Nii:e-tenths of the quartz crushed in Cali- 

 fornia is pulverized by stamps, of which there are two kinds, 



