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sapphire

(Encyclopedia)sapphire, precious stone. A transparent blue corundum, it is classified among the most valuable of gems. Sapphires are found chiefly in Madagascar, Sri Lanka, and Myanmar and also in Thailand, Tanzani...

silicon

(Encyclopedia)silicon, nonmetallic chemical element; symbol Si; at. no. 14; interval in which at. wt. ranges 28.084–28.086; m.p. 1,410℃; b.p. 2,355℃; sp. gr. 2.33 at 25℃; valence usually +4. Silicon is the ...

corundum

(Encyclopedia)corundum kərŭnˈdəm [key], mineral, aluminum oxide, Al2O3. The clear varieties are used as gems and the opaque as abrasive materials. Corundum occurs in crystals of the hexagonal system and in mass...

Cotonou

(Encyclopedia)Cotonou kōtōno͞oˈ [key], city, capital of Atlantique prov., S Benin, on the Gulf of Guinea. ...

Mostar

(Encyclopedia)Mostar môˈstär [key], city (2013 pop. 65,286), in Bosnia and Herzegovina, on the Neretva River. Its name means “Old Bridge,” referring to the 16th-century stone bridge built by Ottoman sultan S...

Bolzano

(Encyclopedia)Bolzano bōˈtsən [key], city, capital of Bolzano prov., in Trentino–Alto Adige, N Italy, ...

The Dalles

(Encyclopedia)The Dalles dălz [key], city (1990 pop. 11,060), seat of Wasco co., N Oreg., on the Columbia River; inc. 1857. It is a busy inland port; ships passing through the locks at Bonneville Dam (c.50 mi/80 k...

sodium hydroxide

(Encyclopedia)sodium hydroxide, chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a caus...

Saguenay

(Encyclopedia)Saguenay săgˈənā, săgˌənāˈ [key], river, c.125 mi (200 km) long, S Que., Canada. It issues from Lac Saint Jean, or Lake Saint John (c.375 sq mi/970 sq km), in two channels, the Grande Déchar...

lithium

(Encyclopedia)lithium lĭthˈēəm [key] [Gr.,=stone], metallic chemical element; symbol Li; at. no. 3; interval in which at. wt. ranges 6.938–6.997; m.p. about 180.54℃; b.p. about 1,342℃; sp. gr. .534 at 20�...