Meteorites
Meteorite is a general term used for all solid materials that have fallen to the Earth's surface from interplanetary space without being completely vaporized during passage through the atmosphere. Most meteorites come from the asteroid belt between the orbits of Mars and Jupiter. Primitive meteorites (chondrites) preserve valuable evidence about the early history of the solar system.
Intense frictional heating and impact during the object's passage through the atmosphere lead to partial melting and the formation of a spherical meteorite with numerous internal cracks. Only if molten objects are large enough to survive passage through the atmosphere can they reach the ground, so that meteorites are quite rare. They have many features which are useful in differentiating them from terrestrial rocks.
Photomicrograph of Leedy Stony Meteorite
Dewey county, Oklahoma, USA
The Leedy Meteorite shares many characteristics with the Duwun meteorite and consists chiefly of silicate minerals such as olivine, augite and plagioclase.
Widmanstätten Structure shown on an Iron Meteorite
This structure is developed by the intergrowth of two meteorite minerals (kamacite and taenite).
Duwun Meteorite
The Duwun Meteorite, weighing 2.117 kg, fell in Duwon-myeon, Goheung-gun, Jeollanam-do, Korea at 3:47 pm on November 23, 1943. The meteorite, displayed in the Geological Museum of KIGAM, is compositionally of the stony type that preserves information indispensable for the study of the origin and evolution of the solar system. It has a chondritic texture, containing small spherical inclusions (chondrules) and is classified as an L6 chondrite because of its relatively low iron content and high metamorphic grade. Duwun is the Japanese pronunciation of Duwon.
Meteorites have many characteristics that distinguish them from the general rocks of the Earth. Stony meteorites have a higher specific gravity than common rocks and a metallic luster, tinged with black or dark-red on the surface immediately after the fall but, after time, turning partially brown by decolorization. They are coarsely crystalline, having similar compositions to terrestrial rocks such as basalt and dunite and are composed largely of silicate minerals such as olivine, augite and plagioclase. Stony-iron meteorites are composed of nickel-iron and silicates in approximately equal proportions. Iron meteorites are silver gray alloys of iron with nickel, so that they have a greater specific gravity as well as some degree of magnetism. In addition, a Widmanstatten structure is characteristically developed.
According to the Meteorite Catalogue of the British Museum, a total of four recorded meteorites have fallen in Korea. They are the Unkoku Chondrite which fell at Ungok, Jeollanam-do in 1924, the Gyokukei Chondrite at Okgye, Gyeongsangbuk-do in 1930, the Duwun Chondrite(L6) at Duwon in 1943, and an iron meteorite found at Sobaek, Hamgyeongnam-do in 1938. However, with the exception of the Duwun Chondrite, there present whereabouts are unknown.
Iron Meteorite
Namibia
Reddish brown meteorite is composed of iron and nickel.