OTHER. REf^OURCE!^ OF MICHIGAN 107 



has lessened in importance, so that at present g}'psvim 

 goes more largely into the manufacture of gypsum 

 plasters employed in the building-trades, plaster- 

 board, fire-proofing and calcimines.^ In 1916, mixed 

 wall-plaster constituted the most important of these 

 gypsum products, its value being then G2.7 per cent 

 of the total of raw and calcined products of the 

 State. Stucco had 26.2 per cent of the total value 

 of gypsum products in that year. In 1916 five 

 mines, two quarries and eight mills were reported 

 by the State Geologist in operation. Kent County 

 is the main location of the industry, since the gypsum 

 formations here are extensive and accessible. Still 

 other gypsum beds exist in Iosco, Arenac, Ionia, 

 Tuscola, and Eaton counties in the southern penin- 

 sula, and near St. Ignace, Mackinac County and on 

 St. Martin's and adjacent islands of the northern 

 peninsula. The g}-psum beds of the State have been 

 officially described as inexhaustible. The production 

 for 1916 was 457,375 tons, and in 1919, 339,125 tons. 

 This is the maximum yearly output. The total 

 production of the United States for that year was 

 2,750,000 short tons. New York was then the largest 

 producer of gypsum, Iowa second, and Michigan 

 third.=^ 



At a number of localities in Michigan are situated 

 mineral springs of considerable therapeutic reputa- 

 tion. In 1911 twenty-two mineral springs were re- 



^ "Mineral Resources," Midi.. 1916, 161. 

 *U. S. Geol. Survey: "Mineral Resources," 1916, Pt. 11., 

 255. 



