154 MINERALS YEARBOOK

 The Waco district (in Kansas) shipped 2,063 tons of sphalerite in 1931;
all mines and mifis were idle in 1932, and no shipments were made from stocked
concentrates.
 Kentucky.—The fluorspar mines in Kentucky made no shipments of lead
concentrates in 1931 or 1932. Shipments in 1930 were 184 tons having a recoverable
content of 101 tons of lead.
 Shipments of 137 tons of zinc carbonate and silicates were made in
1932 from mines near Marion, by Roberts & Frazer and Avery H.
Reed; the' recovered zinc content was 46 tons. , The ore mined by
Avery H. Reed is a mixed zinc carbOnate and lead carbonate.
 Michigai~.—In 1932 the mines of Michigan produced 1,142,775 tons of
rock yielding 79,753,030 pounds of mineral, from which 54,396,108 pounds
of refirnid copper were obtained. The production was ' less than half that'
recorded for 1931.' Adverse industrial po~iditions throughout the world caused
a severe contraction in demand for copper, and an unfavorable balance between
supply ' and demand resulted. A new low price for copper ' was established
in 1932, and virtually all copper mines in the country were operated at a
loss. Owing to these conditiOns the Michigan State Tax Commission reduced
the assessed ,valuation of the mines in Houghton and Keweenaw Counties during
the year from $28,562,661 to $19,992,470; Houghton County mines were valued
at $14,132,470 compared with $20,347,661 in 1931 and. Keweenaw County mines
at $5,860,000 compared. with $8,215,000 i~i 1931. The assessed valuation
of Calumet & IJecla properties in Houghton County was reduced from $14,650,000
to $10,580,000 and in Keweenaw County frOm $5,575,000 to $4,040,000. Copper
Range was reduced from $2,765,000 to $1,900,000.; Isle Royale from $950,000
to $645,000; Quincy from $900,000 to $435,000; Arcadian from $50,000 to $25,000;
La Salle from $80,000 to $25,000; Superior ' from. $20,000 to $10,000; Mohawk
from $1,850,000 to $1,380,000; Seneca from $700,000 to $350,000; and Douglass
Copper from $40,000 to $30,000.
 Mining companies in Michigan made every effort to reduce the cost of production
.by selective mining, abandonment of exploration and construction work, reduction
in salaries and wages, etc. The grade of rock mined increased from 1.27 percent
in 1930 to 1.65 percent in 1931 and to 2.38 percent in 1932. Selective mining
and the failure of the Calumet & Hecla Consolidated Copper Co. to treat
copper sands in 1931 and 1932 were responsible for this increase. The average
grade of rock for the district in 1932 was considerably higher than in any
previous year* since the compilation of mine figures was begun by the U.S.
Geological Survey in 1906, due principally to the mining of high-grade rock
from shaft pifiars and old backs in the conglomerate branch of Calumet &
Hecia. According to Butler and Burbank,1 who recorded the grade of rock produced
by individual mines in the Lake Superior district from 1845 through 1925,
this mine produced rock yielding 66.6 pounds of copper to the ton in 1897
(slightly higher than the 65.53 pounds reported for it in 1932) and produced
no rock of such high grade after that time.

1 Butler, B. S., and Burbank, W. S., The Copper Deposits of Michigan: U.S.
Geol. Survey Prof. Paper
144, 1929. p. 80.