THE MINERAL INDUSTRY OF MONTANA 497 
 
as a binder in pelletizing taconite iron ore concentrate. Some bentonite
was produced near Glasgow, Valley County, by Brazil Creek Bentonite Co. for
use in lining irrigation canals. The company announced that A—D—M
Chemicals Division, Ashland Oil & Refining Co., planned to construct
a 300,000-ton-per-year processing plant on the company property 18 miles
southwest of Glasgow. Plans were to process the bentonite into grades suitable
for binders at the Minnesota Mesabi Range taconiteprocessing plants. Other
exploration and development for bentonitic clays included Peter Kiewit Sons'
Co. development of bentonite deposits near Harlem, Blame County, and American
Colloid Co. locating and leasing lands for mining bentonite south of Malta,
Phillips County. 
 
 Fluorspar.—Roberts Mining Co., the only producer, continued to mine
fluorspar in Ravalli County. Ore from the Crystal Mountain mine was trucked
26 miles to a sizing and heavy~media separation plant at Darby. Metallurgical-grade
fluorspar from the milling operation was marketed largely to the steel industry.

 
 Gypsum.—The tonnage of gypsum mined decreased 23 percent below the
1966 total. Gypsum mined near Heath, Fergus County, from the Shoemaker underground
mine by United States Gypsum Co. was calcined and marketed as ground gypsum.
Gypsum produced by Bridger Gypsum Co. from an underground mine near Bridger,
Carbon County, was sold for agricultural purposes. 
 
 Lime.—Output of lime declined 37 percent, and value was 17 percent
below the 1966 figures. The drop was related largely to the copper strike
which resulted in less lime produced for metallurgical use and for water
treatment, although lime used in manufacturing sugar, also was below the
previous year output. 
 Lime was manufactured in Deer Lodge County by The Anaconda Company for metallurgical
use and for water treatment. Limestone for the operation came from the company
Browns quarry near the lime plant. Holly Sugar Corp., at plants in Big Horn
(Hardin) and Richland (Sidney) Counties, and The Great Western Sugar Co.
at a plant in Yellowstone County (Billings) manufactured lime for use in
sugar refining. All three sugar-refining op 
erations utilized limestone from the Warren quarry (Carbon County) of Big
Horn Limestone Co. 
 The Anaconda Company announced plans to revamp the inoperative Manganese
Development Co. kilns at Butte to manufacture l'ime. Low-magnesium limestone
from a quarry west of Drummond, Granite County, was expected to be used at
the proposed lime plant and lime slurry was to be transported from the plant
3 miles by rail to the copper concentrator also at Butte. 
 
 Phosphate Rock.—The quantity of marketable phosphate rock production
increased 8 percent; but value declined 14 percent, largely because of lower
values for material marketed from phasing out mining operations in Beaverhead
County. Mining continued to be conducted in Beaverhead, Granite, Powell,
and Silver Bow Counties. 
 Phosphate rock from the Canyon Creek and East La Marche mines in Beaverhead
County arid the Maiden Rock mine in Silver Bow County, all near Meirose,
was hauled 23 miles to the Silver Bow elemental phosphorus plant of Stauffer
Chemical Co., Industrial Chemical Division, where it was washed and reduced
to elemental phosphorus. The phosphorus, kept in the molten state by means
of steam-heated storage tanks, was pumped from the tanks to rail tank cars
for shipment to company processing plants at Chicago Heights, Ill., and South
Gate and Richmond, Calif. 
 In October, after mining phosphate rock in Montana since 1951 to feed its
elemental phosphorus plant at Silver Bow, Stauffer started phasing out its
underground phosphate operations near Melrose in favor of low-cost surface
mining in the southeast Idaho section of the phosphate field. Long-range
plans by Stauffer Chemical Co. include installing both beneficiadon and calcining
equipment at Soda Springs, Idaho, to produce high-quality acid-grade rock.
In July Stauffer Chemical Co. had purchased the Terteling Co. holdings of
phosphate rock covering more than 8,000 acres of Federal and State leases
and permits near Soda Springs, Idaho. The deposit, minable by strip or surface
methods and containing an estimated 100 million tons of furnace- and acid-grade
rock, insures the finn's phos