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anemia

(Encyclopedia)anemia ənēˈmēə [key], condition in which the concentration of hemoglobin in the circulating blood is below normal. Such a condition is caused by a deficient number of erythrocytes (red blood cell...

sulfate

(Encyclopedia)sulfate, chemical compound containing the sulfate (SO4) radical. Sulfates are salts or esters of sulfuric acid, H2SO4, formed by replacing one or both of the hydrogens with a metal (e.g., sodium) or a...

chalcopyrite

(Encyclopedia)chalcopyrite pīrīˈtēz, pə– [key], brass-yellow mineral, sometimes with an iridescent tarnish. It is a sulfide of copper and iron, CuFeS2 . It crystallizes in the tetragonal system but is usua...

Wrangell Mountains

(Encyclopedia)Wrangell Mountains, S Alaska, extending c.100 mi (160 km) SE from the Copper River to the Canadian border, where they meet the St. Elias Mts. Mt. Blackburn (16,523 ft/5,036 m) is the highest peak. The...

Sudbury, city, Canada

(Encyclopedia)Sudbury, city (1991 pop. 92,884), central Ont., Canada. It is the center of Canada's largest mining region, which produces much of the world's nickel and large quantities of copper, platinum, gold, si...

oxygen

(Encyclopedia)oxygen, gaseous chemical element; symbol O; at. no. 8; interval in which at. wt. ranges 15.99903–15.99977; m.p. −218.4℃; b.p. −182.962℃; density 1.429 grams per liter at STP; valence −2. T...

Man, town, Côte d'Ivoire

(Encyclopedia)Man, town (1996 est. pop. 112,600), W central Côte d'Ivoire, at the foot of the Toura Mts. It is an administrative and commercial center for a region producing coffee, cacao, kola nuts, rice, and cas...

group

(Encyclopedia)group, in mathematics, system consisting of a set of elements and a binary operation a∘b defined for combining two elements such that the following requirements are satisfied: (1) The set is closed ...

Tsumeb

(Encyclopedia)Tsumeb tso͞oˈmĕb [key], town (1991 pop. 16,211), N Namibia. It is the commercial and distribution center for a region where copper, lead, and zinc are mined. ...

sodium

(Encyclopedia)sodium, a metallic chemical element; symbol Na [Lat. natrium]; at. no. 11; at. wt. 22.98977; m.p. 97.81℃; b.p. 892.9℃; sp. gr. 0.971 at 20℃; valence +1. Sodium is a soft, silver-white metal. Ext...