pseudomorph

/sooh"deuh mawrf'/, n.
1. an irregular or unclassifiable form.
2. a mineral having the outward appearance of another mineral that it has replaced by chemical action.
[1840-50; PSEUDO- + -MORPH]

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      mineral formed by chemical or structural change of another substance, though retaining its original external shape. Although pseudomorphs give the appearance of being crystalline, they are commonly granular and waxy internally and have no regular cleavage; those that are crystalline have optical properties different from those required by their outward form.

      Pseudomorphs are formed by substitution, deposition, or alteration. In the formation of a pseudomorph by substitution, the original substance has been gradually removed and simultaneously replaced by another. A common example of this is petrified wood, in which all the cellulose fibres have been replaced by silica, even those in the bark. Pseudomorphs can be formed by deposition of one mineral on the surface of crystals of another (see also epitaxy). Alteration pseudomorphs may be formed in several ways: from a change in internal crystal structure without a change in chemical composition (these pseudomorphs are called paramorphs; e.g., aragonite becomes calcite, and brookite becomes rutile); by the loss of an ingredient from the original compound (e.g., cuprite loses oxygen to form copper); by the addition of an ingredient to the original compound (e.g., anhydrite adds water to form gypsum, and cuprite adds carbon dioxide and water to form malachite); and by an exchange of constituents (e.g., feldspar loses potassium silicate and gains water to become kaolinite).

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Universalium. 2010.

Look at other dictionaries:

  • Pseudomorph — Pseu do*morph, n. [See {Pseudomorphous}.] 1. An irregular or deceptive form. [1913 Webster] 2. (Crystallog.) A {pseudomorphous crystal}, such as a crystal consisting of quartz, but having the cubic form of fluor spar, the fluor crystal having… …   The Collaborative International Dictionary of English

  • pseudomorph — [so͞o′də môrf΄] n. [< Gr pseudomorphos, having a false form: see PSEUDO & MORPH] 1. a false or irregular form 2. a mineral possessing the external form characteristic of another pseudomorphism [soo΄dəmôr′fiz΄əm] n. pseudomorphous… …   English World dictionary

  • Pseudomorph — In geology, a pseudomorph is a mineral compound resulting from a substitution process in which the appearance and dimensions remain constant, but the mineral which makes up the chief component of the compound is replaced by another. The name… …   Wikipedia

  • pseudomorph — noun A mineral that formed by replacement of an existing mineral (or organic matter) such that the new mineral has the appearance and dimensions of the original. Petrified wood is a silicic pseudomorph of the original wood …   Wiktionary

  • pseudomorph — noun Etymology: probably from French pseudomorphe, from pseud + morphe morph Date: 1849 1. a mineral having the characteristic outward form of another species 2. a deceptive or irregular form • pseudomorphic adjective • pseudomorphism noun •… …   New Collegiate Dictionary

  • pseudomorph — A mineral found crystallized in a form that is not proper to it but to some other mineral. [pseudo + G. morphe, form] …   Medical dictionary

  • pseudomorph — pseu|do|mọrph 〈Adj.〉 Pseudomorphose aufweisend, durch Pseudomorphose entstanden * * * pseu|do|mọrph <Adj.> (Mineral.): Pseudomorphose aufweisend …   Universal-Lexikon

  • pseudomorph — pseu|do|mọrph 〈Adj.; Min.〉 Pseudomorphose aufweisend, durch Pseudomorphose entstanden …   Lexikalische Deutsches Wörterbuch

  • pseudomorph — pseu|do|morph <zu ↑...morph> Pseudomorphose zeigend …   Das große Fremdwörterbuch

  • pseudomorph — pseu·do·morph …   English syllables

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