010.1. MINERALS YEARBOOK, 1967the sole commercial producer of quicklimeand
hydrated lime. At its plant near Buf 
 
The State continued as one of the Nation's major producers of gypsum and
gypsum products, ranking third in the United States in the quantity of crude
gypsum produced. 
 Gypsum was produced from an underground mine, operated by United States
Gypsum Co. in Des Moines County, and from four open-pit mines, operated in
Webster County by Bestwall Gypsum Division, Georgia-Pacific Corp.; The Celo~
tex Corp.; National Gypsum Co.; and United States Gypsum Co. All companies
produced a wide variety of gypsum products. Uncalcined gypsum was sold for
portland cement retarder, agricultural use, brewer's fixe, fillers, and other
uses. Calcined gypsum was used primarily for building purposes including
base-coat plaster, veneer plaster, mill-mixed basecoats, gaging and molding
plasters, prepared finishes, roof deck plasters, lath, wall board, sheathing,
laminated board, and formboard. Others uses of calcined-gypsum products included
plate glass and terra cotta works, dental and orthopedic plaster, industrial
molding, art, and casting plasters. 
 Natural gas was used as the sole or primary fuel at all of the five calcining
plants in the State. Calcining equipment utilized included 22 kettles and
four Hydrocal cylinders. 
 The Iowa State University Center for Industrial Research & Service conducted
exploration drilling for gypsum near Albia. Results indicated a deposit consisting
mostly of anhydrite at a depth of about 350 to 400 feet. The drilling was
financed by grants from the Federal Economic Development Administration and
the Albia Chamber of Commerce. 
 
 Lime.—Total production of quicklime and hydrated lime decreased 10
percent in tonnage and 12 percent in value from that of 1966. 
 American Crystal Sugar Co. produced quicklime for internal use in sugar
refining at its Mason City plant in Cerro Gordo County. Purchased high-calcium
limestone was burned in the company's shaft kiln, utilizing coke as fuel.

 Linwood Stone Products Co., Inc., was 
falo in Scott County three rotary kilns were used for burning the high-calcium
limestone obtained locally from companyowned sources. Coal and natural gas
were used as fuel. 
 Consumption of lime in Iowa exceeded the State's production by 14 percent,
with Missouri being the principal source of shipments into the State. 
 Sales of Iowa-produced lime were principally to Iowa markets, which received
47 percent of the shipments, and to Illinois and Indiana. 
 Of Iowa's lime production, 41 percent was used primarily for water purification,
38 percent for steelmaking, and the remainder for construction, sugar refining,
sewage treatment, and paper and pulp manufacture. 
 
 Perlite.—Crude perlite, mined outside the State, was expanded at plants
operated by the gypsum producers in Webster County. The expanded product
was used principally in manufacturing lightweight building plaster. 
 
 Sand and GraveL—Sand and gravel production decreased 10 percent in
quantity and 9 percent in value, from 1966 levels. Production for paving
use decreased over 12 percent. Since paving required 67 percent of the State
total sand and gravel production, the decrease in interstate highway construction
represented most of the decline in total production from the previous year.
Production for building, the other major use of sand and gravel (representing
25 percent of the State total), increased 1 percent. 
 Sand and gravel production was reported in 78 counties, from 259 commercial
and 50 Government-and-contractor operations. Polk, Story, Lyon, Sioux, and
Sac Counties ranked in that order as the five leading sand and gravel producers,
accounting for over 30 percent of the State total. 
 Overall average unit value for sand and gravel was $0.93 per ton, approximately
the same as for 1966. 
 Approximately 97 percent of the total commercial sand and gravel shipments
were transported by truck, with the remainder by rail and water.