1 Data regarding producers of natural gas, natural gas liquids, and petroleum
are not available. 
2 All companies listed under "Clays and shale" operated pits and processing
plants; products manufactured are shown under "Remarks" column. 
 ~ for International Salt Co., Inc., who operated an underground salt mine,
aS companies listed processed well brines and recovered the products shown
under "Remark column." 
4 Portable plants were operated at the listed locations unless otherwise
specified. 
5 All companies operated stationary plants at the listed locations and produced
crushed limestone. 
 Do Kalamazoo Kalamazoo       
 Do Sturgis St. Joseph        
 Do Keeler and Lawrence Van Buren       
Silver: 
   White Pine Copper Co White Pine Ontonagon       
Smelters: 
 Calumet & Hecla, Inc Calumet Houghton Primary copper smelter. 
 Quincy Mining Co Hancock    do Do. 
 White Pine Copper Co White Pine Ontonagon Do. 
Stone: 
Limestone: 
 Drurnmond Dolomite, Inc De Tour Village Chippewa        
 Dundee Cement Co Dundee Monroe          
 The France Stone Co Monroe    do          
Huron Cement Co., Division of National Gyp- Alpena Alpena         sum Co.

Inland Lime & Stone Co., Division of Inland Manistique Mackinac     
  
Steel Co. 
 Do do Schoolcraft______ 
 The Michigan Stone Co Maybee and Ottawa Lake     Monroe 
 Penn-Dixie Cement Corp Petoskey                  Emmet 
 Presque Isle Corp Alpena Presque Isle______ 
 United States Steel Corp Cedarville                 Mackinac        
 Do Rogers City                Presque Isle_____ Recovered sulfur: 
 Leonard Refineries, Inc Alma Gratiot Hydrofining process. 
   Marathon Oil Co Detroit Wayne Parsons process. 
   Mobil Oil Co., Inc Trenton    do Claus process. 
Exfoliated vermiculite: 
   Zonolite Division, W. R. Grace & Co Dearborn    do          
 
 
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