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bauxite

(Encyclopedia)bauxite bôkˈsīt, bŏkˈ– [key], mixture of hydrated aluminum oxides usually containing oxides of iron and silicon in varying quantities. A noncrystalline substance formerly thought to be a minera...

abrasive

(Encyclopedia)abrasive, material used to grind, smooth, cut, or polish another substance. Natural abrasives include sand, pumice, corundum, and ground quartz. Carborundum (silicon carbide) and alumina (aluminum oxi...

grinding

(Encyclopedia)grinding, process by which surface material is removed from an object, usually metal, by the abrasive action of a rotating wheel or a moving belt that contains abrasive grains. A grinding wheel can be...

bronze, in metallurgy

(Encyclopedia)bronze, in metallurgy, alloy of copper, tin, zinc, phosphorus, and sometimes small amounts of other elements. Bronzes are harder than brasses. Most are produced by melting the copper and adding the de...

Glen Roy

(Encyclopedia)Glen Roy, valley, Highland, W Scotland, E of Loch Lochy. The Parallel Roads, three terraces on each side of the valley at corresponding heights, are believed to mark receding levels of a lake that onc...

boron

(Encyclopedia)boron bōrˈŏn [key] [New Gr. from borax], chemical element; symbol B; at. no. 5; interval in which at. wt. ranges 10.806–10.821; m.p. about 2,300℃; sublimation point about 2,550℃; sp. gr. 2.3 ...

Sacramento, river, United States

(Encyclopedia)Sacramento, longest river of Calif., c.380 mi (610 km) long, rising near Mt. Shasta, N Calif., and flowing generally SW to Suisun Bay, an arm of San Francisco Bay, where it forms a large delta with th...

Gudbrandsdalen

(Encyclopedia)Gudbrandsdalen go͝odˈbrändsdälˌĕn [key], valley region of Oppland co., S central Norway. It extends c.100 mi (160 km) from the Dovrefjell southeastward to Lillehammer on Mjøsa lake. A rich agri...

firebrick

(Encyclopedia)firebrick, brick that can withstand high temperatures, used to line flues, stacks, furnaces, and fireplaces. In general, such bricks have high melting points that range from about 2,800℉ (1.540℃) ...

San Fernando, city, United States

(Encyclopedia)San Fernando, city (1990 pop. 22,580), Los Angeles co., S Calif., in the San Fernando valley; inc. 1911. Among its industries are clothing and electronics. The valley, first entered by Europeans in 17...