Source: Schedule 4, Products of Industry, for Port Austin Township, Huron County.
1870 schedule lists W. H. Cooper and Company as manufacturers of grindstones and whet stones, with a capital stock of $14,000. Power was 30 h.p. steam operation. Usual machines were lathes, gang of saws and grinder. Cooper and Co. used 3 lathes, 20 saws, 1 grinder, 1 engine. They employed 34 males above 15 years of age. Total wages paid per year was $11,000 for a 9-1/2 month work year. Raw materials were stone and wood valued at $1,240. Productions were 1,400 tons of grindstones valued at $16,800.
1880 schedule reports the Lake Huron Grind and whetstone Company, who produced grindstones valued at $35,000; and Worthington and Sons, who produced grindstones valued at $42,000.
Letter from Edward Kirkby, Geological Survey, Department of Conservation, reports 800 men employed in the quarries and mills, taken from page 22 of “Huron County centennial History, 1859-1959,” courtesy of Michigan Bell Telephone Company.
Reported on page 207 of Annual Report of the Commissioner of Mineral Statistics (1882) in the state of Michigan that 3,000 tons of grindstones were produced annually. The next mention of production may be found on page 157 of the annual report for 1895 when 2,924 tons of grindstones valued at $23,000; 14,357 brushed grindstones valued at $5,742.80; 6,555 gross of scythe stones valued at $13,110; and 1,100 cords of rubble stones valued at $2,757 were produced.
The 1897 production figures from the Annual Report of the Commissioner of Mineral Statistics and the 1898-1899 may be found on page 207 of “Geological report on Huron County, Michigan” by A. C. Lane, Michigan Geological Survey Volume 7, part 2, 1900.
Grindstone City Port Austin
1897 1898 1899 1897 1898 1899
Loose grindstones (tons) 4,054 3,606 3,855 2,000 1,232 1,576
Mounted (pieces) 6,320 11,292 5,292 8,532
Scythe stone (gross) 5,917 3,957-1/2 4,259 2,500 1,316 1,951
No production statistics were found for the years after 1899. Part of this lack of information is due to only two companies operating and each wishing to keep its production figures confidential and away from their competitors.
See “Our Rock Riches”, Michigan Geological Survey Bulletin 2.

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