词条 | Ironstone |
释义 |
DescriptionFreshly cleaved ironstone is usually grey. The brown external appearance is due to oxidation of its surface. Ironstone, being a sedimentary rock is not always homogeneous, and can be found in a red and black banded form called tiger iron, sometimes used for jewelry purposes. Sometimes ironstone hosts concretions or opal gems. OccurrenceIronstone occurs in a variety of forms. The various forms of ironstone include siderite nodules; deeply weathered saprolite, i.e. (laterite); and ooidal ironstone. UsesIronstone as a source of ironIronstone, although widespread, is a limited source of iron (Fe). Historically, most of British iron originated from ironstone, but it is now rarely used for this purpose because it is far too limited in quantity to be an economic source of iron ore. CeramicsIronstone's oxide impurities render it useless as a component in ceramics: the "ironstone china" of Staffordshire and American manufacture, a fine white high-fired vitreous semi-porcelain, commonly used for heavy-duty dinner services in the 19th century,[3] depends on the whiteness of its body.{{clarify|reason=That sentence makes no sense. Ironstone china depends on the whiteness of its body for WHAT?|date=July 2017}} Its "iron" quality is in its resistance to chipping, not in any ingredient in its manufacture. In constructionThe stone can be used as a building material. Examples include the parish churches at Kirby Bellars, Eydon Hall and South Croxton in Leicestershire. See also
References{{Commons category|Ironstone}}1. ^U.S. Bureau of Mines Staff (1996) Dictionary of Mining, Mineral, & Related Terms. Report SP-96-1, U.S. Department of Interior, U.S. Bureau of Mines, Washington, D.C. 2. ^Neuendorf, K. K. E., J. P. Mehl Jr., and J. A. Jackson, J. A., eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. {{ISBN|0-922152-76-4}} 3. ^G. Bernard Hughes, English and Scottish Earthenware, Abbey Library 2 : Sedimentary rocks|Iron ores |
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