Physics

Lanthanum Definition Lanthanum is a soft, malleable, silvery-white metallic element of the lanthanide series. It is the eponym of the lanthanide series, a group of…

Yttrium Definition Yttrium is a silvery metallic element found in the same ores as elements of the lanthanide series. It is almost always found in…

Bastnäsite Definition Bastnäsite is a rare yellow to reddish-brown mineral consisting of a carbonate of fluorine and several lanthanide metals. It occurs in association with…

Neodymium Definition Neodymium is a shiny, silvery metallic element of the lanthanide series. It is present in significant quantities in the ore minerals monazite and…

Scheelite Definition Scheelite is a white, brownish, or greenish mineral, usually fluorescent, consisting of calcium tungstate in tetragonal crystalline form with some tungsten often replaced…

Tungsten Definition Tungsten is a hard, gray to white metallic element that is very resistant to corrosion. It has the highest melting point of all…

Rhenium Definition Rhenium is a very rare, dense, silvery-white metallic element with a very high melting point. It is used to make catalysts and electrical…

Diorite Definition Diorite is a gray, coarse-grained plutonic rock. Diorite consists mainly of sodium-rich plagioclase and one or more mafic minerals such as biotite, hornblende,…

Monzonite Definition Monzonite is an igneous rock composed chiefly of plagioclase and orthoclase, with small amounts of amphibole, pyroxene, and biotite. Monzonite contains little or…

Syenite Definition Syenite is a light-colored, coarse-grained igneous rock consisting primarily of alkali feldspar together with some mafic minerals, especially hornblende. Unlike most igneous rocks,…

Chondrite Definition Chondrite is a stony meteorite that contains chondrules embedded in a fine matrix of the silicate minerals olivine and pyroxene. About 85 percent…

Meteorite Definition Meteorite is a meteor that reaches the Earth’s surface because it has not been burned up by friction with the atmosphere. Meteorites are…