The Mexican mining journal . face. It is rich in gold-bearing veins and especially in placers, most of thesebeing local accumulations of detrital material from thedecay of veinstone and impregnated rock. The districtwas known for the great extent and richness of thesedeposits long before the Spanish occupation and, inits numerous gold-bearing veins some rich mines weredeveloped, a few being still in operation. Altar is themost arid region of Sonora, and mining is greatlyhampered by th-i scarcity of surface water; yet thatobstacle is frequently overcome by pumping fromwells or rivers- In the ea
The Mexican mining journal . face. It is rich in gold-bearing veins and especially in placers, most of thesebeing local accumulations of detrital material from thedecay of veinstone and impregnated rock. The districtwas known for the great extent and richness of thesedeposits long before the Spanish occupation and, inits numerous gold-bearing veins some rich mines weredeveloped, a few being still in operation. Altar is themost arid region of Sonora, and mining is greatlyhampered by th-i scarcity of surface water; yet thatobstacle is frequently overcome by pumping fromwells or rivers- In the early working of the placers,millions of dollars were taken out without the aid ofwater, by the batea, or wooden gold pan, the nativesbeing very expert in the use of this implement. Theintroduction of the dry washer from Hungary in 1815,has geatly facilitated the extraction of placer machines, of which various kinds have beendevised, combine air-blast and agitation, the air from By, 1915. MEXICAN MINING JOURNAL. 245. 246 MEXICAN MINING JOURNAL. July, 1915. a bellows or votary blower passing through the clothbottom of an inclined table crossed by wooden riffles,down which the auriferous earth is made to travel byconstant agitation. The blast carries away the dustarid the gold is caught by the riffles. Dry methodscan, of course, be pursued only in the dry season, whenthe dirt is free from moisture, artificial drying beingas yet not in use. This district is richly mineralized, except, possibly,in a belt about 50 miles wide along the coast from Li-bertad southward. Within this area few mineral de-posits have yet found. It is, however, a desertwithout surface water, and this important article mustbe carried by the traveler, both for himself and forhis horses or mules. It is possible that, when morewells have been established, and mere existence be-comes less of a problem for the prospector, many goodorebodies may be found in this coastal plain. Altar, the capital of t
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