280 RESOURCES 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 who 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 large stone wheels which roll round on their 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 amalga- 
mating with the Chilean mill, are very similar to those of the 
arastra. The Chilean mill, however, is rarely used in Califor- 
nia; the arastra being considered far preferable, 
§ 210. Stamps.—Nine-tenths of the quartz crushed in Cali- 
fornia is pulverized by stamps, of which there are two kinds, 
