336 



UNITED STATES MINERAL RESOURCES 



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Figure 40. — Production of materials used as structural lightweight aggregates in the United States, 1940-70. 

 New construction. — Value of total new construction, exclusive of maintenance and repair; data from Statistical Abstracts 



of the United States, 1940-70. 

 Total output. — Tonnage of all materials used as structural lightweight aggregates: A, Estimate in Rock Products, v. 66, no. 



1, p. 83, 1962. B, Estimate by R. A. Grancher in Rock Products, v. 72, no. 12, p. 62, 1969 (lacks data for slate, 1960- 



63). C, Estimate by Harvey Smith in Mining Engineering, v. 24, no. 1, p. 53, 1972. 



