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Zimbabwe
Zimbabwe [Bantu,=stone houses], ruined city, SE Zimbabwe, near Fort Victoria. It was discovered by European explorers c.1870, and some believed it the biblical Ophir, where King Solomon had his mines. From 1890 to 1900 some 100,000 gold mining claims were staked out there, but all proved barren. Mo...
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chalcopyrite
chalcopyrite or copper pyrites , brass-yellow mineral, sometimes with an iridescent tarnish. It is a sulfide of copper and iron, CuFeS 2 . It crystallizes in the tetragonal system but is usually found in the massive form. Chalcopyrite is of primary origin and occurs in igneous and metamo...
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supernova
supernova a massive star in the latter stages of stellar evolution that suddenly contracts and then explodes, increasing its energy output as much as a billionfold. Supernovas are the principal distributors of heavy elements throughout the universe; all elements heavier than iron are produced in ...
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molybdenite
molybdenite , a mineral, molybdenum disulfide, MoS 2 , blue-gray in color, with a metallic luster and greasy feel. It occurs in crystals of the hexagonal system but more commonly in scales, grains, or foliated or massive form. It has an excellent basal cleavage and the laminae are flexible. It is fo...
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graphite
graphite , an allotropic form of carbon , known also as plumbago and black lead. It is dark gray or black, crystalline (often in the form of slippery scales), greasy, and soft, with a metallic luster. It is a good conductor of electricity and does not fuse at very high temperatures or burn easily. ...
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pyrite
pyrite or iron pyrites , pale brass-yellow mineral, the bisulfide of iron, FeS 2 . It occurs most commonly in crystals (belonging to the isometric system and usually in the form of cubes and pyritohedrons) but is also found in massive, granular, and stalactite form. In spite of its nickname, "...
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Ceres
Ceres , in astronomy, a dwarf planet, the first asteroid to be discovered. It was found on Jan. 1, 1801, by G. Piazzi . He took three distinct observations; on the basis of these the mathematician Gauss calculated Ceres' orbit with such accuracy that it was found one year later within 0.5° ...
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star cluster
star cluster a group of stars near each other in space and resembling each other in certain characteristics that suggest a common origin for the group. Stars in the same cluster move at the same rate and in the same direction. Two types of clusters can be distinguished—open clusters, also cal...
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W and Z particles
W and Z particles elementary particles that mediate, or carry, the fundamental force associated with weak interactions . The discovery of the W and Z particles at CERN near Geneva, Switzerland, in the early 1980s was an important confirmation of electroweak theory, which unifies the electr...
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turquoise
turquoise hydrous phosphate of aluminum and copper, Al 2 (OH) 3 PO 4 ·H 2 O+Cu, used as a gem. It occurs rarely in crystal form, but is usually cryptocrystalline. Turquoise is opaque and has a waxy luster; the color varies from greenish gray to sky-blue. The sky-blue varieties are the most v...
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