8
 wide and 8-1/2 feet thick. Nearly 70 percent of the

 copper mined in Michigan in 1861 was mass copper, but as

 time passed the copper content of Michigan ore fell; by

 1890 mass copper had become quite scarce.

 As ore ran thin and mines grew deeper,9 mines

 were forced to close. Today most Michigan mines have

 been abandoned; shaft houses that remain stand silent,

 and only a small mine at White Pine remains in operation.

 Rock piles are to be seen alongside almost every town,

 and old company houses, now privately owned, remain; but

 most of the people have gone or are leaving. The copper

 country of Upper Michigan is a thing of the past; the

 mines emptied of their rich ores.1 Mining has moved to

 the West.

 Arizona, which held third place in copper output

at the turn of the century, behind Michigan and Montana,

now is in first place by a wide margin. In 1969 Arizona

mines contributed 52 percent of domestic copper, Utah

was a distant second at 19 percent, Montana fifth at 6


 8Ibid., p. 232.

 9The Calumet and Hecla Quincy mine, whose shaft
house still stands atop a tall hill overlooking the
cities of Houghton and Hancock, would become more than
a mile deep by the 1930s.

 10Significant deposits remain in the Upper
Peninsula and account for a substantial share of
remaining United States reserves; but because
mineralization is erratic and many of the outcrops are
concealed, exploitation of remaining deposits is
difficult.