The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part III. Earthy minerals

Collection:: Economics Books

ECONOMIC GEOLOGY 11-inch diameter iron cylinder. The stones are tested both dry and wet. The tests for road metal recommended by the United States Department of Agriculture and the Canadian Geological Survey (Mem. G.S. Canada, 8s, 1916, by L. Reinecke and 114, 1919, by H. Gauthier) are based upon the specific gravity, the percentage of wear under attrition ina rotating cylinder, hardness measured by loss in weight when pressed against a revolving iron disc armed with coarse sand, the absorption of water by 48 hours’ immersion, and toughness. The grade of toughness is tested by the height in centimetres through which a two-kilogram hammer must fall to break a cylinder of the stone, an inch in diameter and height. According to the U.S. Office of Public Roads, stone for roads that are traversed by less than 100 vehicles a day may have a toughness of 5-0, by 100 to 250 vehicles a day of 10-13, and by more than 250 vehicles a day a toughness of 10-19, according to the different setting of the macadam. [84

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