California brick

Humboldt Clay Manufacturing Company


Around 1909, the Humboldt Clay Manufacturing Company was organized by Harrison M. Mercer, president, and Charles J. Dunten, manager, of Eureka. Mercer was the president of Mercer-Fraser Company, Eureka. Clay was mined on Ryan Slough, east of Eureka on 1 3/4 acres of land. There is no description of the plant. This company manufactured sand-molded common brick until 1913, when the plant closed. In 1910, these bricks were used in the post office and court house on the corner of H and 5th streets, Eureka. A marked brick was reported by Michael Luther and his photograph is displayed below. Further details on the marked brick is forthcoming.

Humboldt Brick

Common brick is red, mostly uniform in color. Surface is sand-struck with minor white feldspar up to 1/4 inch across. Some sides display a light shade of flash, with minor pits and abrasions. Irregular lip up to 1/8 inch thick occur along the top edges. Edges are nearly sharp, but often chipped, and corners are dull. Top face is pitted and has angled. Bottom face has longitudinal grooves and is marked with thin recessed block letters on two lines. The first line contains the name "HUMBOLT" which is misspelled. The second line contains "C. MFG. CO" with square shaped periods. The interior of the clay body has tiny pits and white feldspar. This brick was made using the sand-molded, soft-mud process. Length 8 1/4, width 4, height 2 3/8 inches.

Humboldt brick
Side and end of the Humboldt brick in the Post Office Building, Eureka.

Humboldt brick
Partial view of the top face of the Humboldt brick in the Post Office Building, Eureka.

Marked face of the Humboldt brick
Marked face of the Humboldt brick. The name Humboldt is misspelled. Photo courtesy of Michael Luther.


Boalich, E.S., Castello, W.O., Huguenin, Emile, Logan, C.A., and Tucker, W.B., The Clay Industry In California, California State Mining Bureau Preliminary Report 7, 1920, p. 47.

Dietrich, Waldemar F., The Clay Resources and the Ceramic Industry of California, California State Mining Bureau Bulletin 99, 1928, p. 80.

Eureka City Directories, 1909-1913.

Luther, Michael, written communications, 2014.

Copyright 2007 Dan Mosier

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