East Grand Forks Clay

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At East Grand Forks the silts are 100 feet deep and extend for miles up and down the Red River valley.  The upper 5 feet is leached and weathered yellow, and this portion has been used for a long time in making cream-colored brick.  On the east side of the [Red] river work has been in progress over 20 years, and at Grand Forks, on the North Dakota side, for an even longer time.  The same company controls the yards in both North Dakota and Minnesota.  Steam shovels and more modern machinery have been installed on the North Dakota side, so that if the market demand is not at its greatest, the Minnesota plant is closed; but the character of the clay is said to be essentially the same at both plants.  The clay slakes at once and has a very low plasticity.  It requires 26 per cent of water

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for molding and shrinks less than 4 per cent on drying.  Its tensile strength is well above 100 pounds to the square inch.  As burned at the Minnesota School of Mines experiment station it gave the following results:

The clay becomes hard at cone 01 (2,066° F.) and reaches viscosity at cone 5 (2,246° F.).  It is capable of being burned to hard, porous brick.  The plant on the Minnesota side of the river has a capacity of about 50,000 brick a day.

Source:
Clays and Shales of Minnesota
Frank F. Grout with contributions by E. K. Soper
United States Geological Survey
Government Printing Office, Washington, D.C., 1919