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Welsbach, Carl Auer, Baron von
(Encyclopedia)Welsbach, Carl Auer, Baron von kärl ouˈər bärōnˈ fən vĕlsˈbäkh [key], 1858–1929, Austrian chemist. He discovered the rare earth elements neodymium and praseodymium (1885) and lutetium (c.1...asthenosphere
(Encyclopedia)asthenosphere ăsthēnˈəsfēr [key], region in the upper mantle of the earth's interior, characterized by low-density, semiplastic (or partially molten) rock material chemically similar to the overl...cowrie
(Encyclopedia)cowrie or cowry both: kouˈrē [key], common name applied to marine gastropods belonging to the family Cypraeidae, a well-developed family of marine snails found in the tropics. Cowries are abundant i...pearl, gem
(Encyclopedia)pearl, hard, rounded secretion formed inside the shell of certain mollusks, used as a gem. It is secreted by the epithelial cells of the mantle, a curtain of tissue between the shell and body mass, an...mother-of-pearl
(Encyclopedia)mother-of-pearl or nacre nāˈkər [key], the iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. Like the pearl it is a secretion of the mantle,...Mollusca
(Encyclopedia)Mollusca məlŭsˈkə [key], taxonomic name for the one of the largest phyla of invertebrate animals (Arthropoda is the largest) comprising more than 50,000 living mollusk species and about 35,000 fos...silicate
(Encyclopedia)silicate, chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may b...seafloor spreading
(Encyclopedia) CE5 Schematic model of the oceanic crust, showing seafloor spreading seafloor spreading, theory of lithospheric evolution that holds that the ocean floors are spreading outward from vast underwate...Dutton, Clarence Edward
(Encyclopedia)Dutton, Clarence Edward, 1841–1912, American geologist, b. Wallingford, Conn., grad. Yale, 1860. After service in the army during and after the Civil War, he was a member (1875–91) of the U.S. Geo...Wilson, J. Tuzo
(Encyclopedia)Wilson, J. Tuzo (John Tuzo Wilson), 1908–93, Canadian geologist and geophysicist, b. Ottawa, Ph.D. Princeton (1936), M.A. Cambridge (1940). He worked for the Geological Survey of Canada (1936–39) ...Browse by Subject
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