Advanced Geography . Hydraulic not nearly so useful as iron. The value of the preciousmetals is largely due to their scarcity. Which of the coins of the United States are made of gold? Whicharc made of silver ? Name some other uses of gold and of silver. What have you learned about the gold-bearing gravels of Cali-fornia ? See lesson 35. Gold is found pure in nature. It is most often takenfrom veins of quartz rock or from old river gravelsformed largely of the washings of quartz veins. Gold is separated from quartz bycrushing the rock and then mixing themass with quicksilver and water
Advanced Geography . Hydraulic not nearly so useful as iron. The value of the preciousmetals is largely due to their scarcity. Which of the coins of the United States are made of gold? Whicharc made of silver ? Name some other uses of gold and of silver. What have you learned about the gold-bearing gravels of Cali-fornia ? See lesson 35. Gold is found pure in nature. It is most often takenfrom veins of quartz rock or from old river gravelsformed largely of the washings of quartz veins. Gold is separated from quartz bycrushing the rock and then mixing themass with quicksilver and water. Thegold and quicksilver soon unite witheach other. The amalgam, or- com-pound of the two metals, is heated andthe quicksilver is thus driven off, leav-ing the gold. Oneof the pictures onthis page shows a-smeltery wherework of this kindis done. Another pictureshows how a streamof water may beused to wear downgold-bearing gravelbeds. Such workis known as hy-draulic gravel, and thegold which it con-tains, are washed into a lo
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