tungsten

A hard, brittle, corrosion-resistant, gray to white metallic element extracted from wolframite, scheelite, and other minerals, having the highest melting point and lowest vapor pressure of any metal. Tungsten and its alloys are used in high-temperature structural materials and wear-resistant tools and machine parts; in electrical elements, notably lamp filaments; and in instruments requiring thermally compatible glass-to-metal seals. Atomic number 74; atomic weight 183.84; melting point 3,422°C; boiling point 5,555°C; specific gravity 19.3 (20°C); valence 2, 3, 4, 5, 6. cross-reference: Periodic Table.

Metallic tungsten has been obtained by means of the electric furnace in a fused state, though not quite compact, and probably not quite pure. It is of rather bright gray color, with metallic luster, specific gravity 18.7, hard, but not sufficiently so to scratch glass, of very high melting-point and softening gradually before fusion, so that it may be welded. It is little acted on by air or water at ordinary temperature, slowly attacked by hydrochloric, hydrofluoric, or sulphuric acid, rapidly by hydrochloric or hydrofluoric acid with addition of nitric acid, and when in powder burns in the air at a red heat.

Chemical symbol, W; atomic weight, 183.5. A metal some of whose ores have long been known (see wolfram and scheelite), but they were supposed to be compounds of tin.

The native tungstate of lime.

A rare element of the chromium group found in certain minerals, as wolfram and scheelite, and isolated as a heavy steel-gray metal which is very hard and infusible. It has both acid and basic properties. When alloyed in small quantities with steel, it greatly increases its hardness. Symbol W (Wolframium). Atomic weight, 183.6. Specific gravity, 18.

Scheelite, or calcium tungstate.

tungstite.

a metallic chemical element (symbol W) with an atomic number of 74. The symbol is derived from the Latin word wolframium.

a heavy grey-white metallic element; the pure form is used mainly in electrical applications; it is found in several ores including wolframite and scheelite