Allophane

Allophane

Allophane is an amorphous hydrous aluminium silicate clay "mineral". Its chemical formula is Al2O3·(SiO2)1.3-2·2.5-3(H2O). Although it has a variable composition and although generally amorphous in structure, it has long been recognized as a mineral and can be identified by its distinctive X-ray diffraction pattern. It was first described in 1816 in Gräfenthal, Thuringia, Germany. Allophane is a weathering or hydrothermal alteration product of feldspars and other primary minerals and has a composition similar to kaolinite. A copper containing variety "cupro-allophane" has been reported.

It forms waxy botryoidal to crusty masses with color varying from white through green, blue, yellow, to brown. It has a Mohs hardness of 3 and a specific gravity of 1.0.

It was named from the Greek "allos" - "other" and "phanos" - "to appear", as it gave a deceptive reaction in the blowpipe flame in old mineralogical testing.

References

* [http://webmineral.com/data/Allophane.shtml Webmineral data]
* [http://www.mindat.org/min-139.html Mindat]


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Look at other dictionaries:

  • Allophane — Allophane[1] Catégorie IX : silicates[2] …   Wikipédia en Français

  • allophane — ● allophane nom féminin Variété d argile colloïdale, mélange de silicates d aluminium hydratés ou prédomine l halloysite, abondante dans les sols développés sur roches volcaniques basiques. ⇒ALLOPHANE, subst. fém. MINÉR. Variété d argile,… …   Encyclopédie Universelle

  • Allophane —   [griechisch phaínesthai »erscheinen«], Singular Allophan der, s, wasserreiche, durch Verwitterung hauptsächlich in jungen Böden, v. a. auf vulkanischen Aschen, gebildete, nahezu amorphe Tonminerale. Allophane bilden sehr kleine Teilchen mit… …   Universal-Lexikon

  • allophane — [al′ō fān΄, al′əfān΄] n. [ ALLO + PHANE, as in Gr allophanēs, appearing otherwise: so named because it changes appearance under the blowpipe] a soft clay mineral, a translucent, hydrous silicate of aluminum, of varying composition and color,… …   English World dictionary

  • allophane — alofanas statusas T sritis chemija apibrėžtis Mineralas. formulė xAl₂O₃·ySiO₂·H₂O; čia x:y = 1:1 atitikmenys: angl. allophane rus. аллофан …   Chemijos terminų aiškinamasis žodynas

  • allophäne Mäuse — allophäne Mäuse,   Mosaikmäuse, Mäuse, die durch Mischung von Zellen genotypisch unterschiedlich befruchteter Eizellen entstehen. Unterschieden sich die ursprünglichen Stämme z. B. in ihrer Pigmentierung, entstehen allophäne Mäuse mit… …   Universal-Lexikon

  • allophane — noun Etymology: Greek allophanēs appearing otherwise, from all + phainesthai to appear, middle voice of phainein to show more at fancy Date: circa 1821 an amorphous translucent mineral of various colors often occurring in incrustations or… …   New Collegiate Dictionary

  • allophane — /al euh fayn /, n. a clay mineral, an amorphous hydrous silicate of aluminum, occurring in blue, green, or yellow, resinous to earthy masses. [1835 45; < Gk allophanés, equiv. to allo ALLO + phan (s. of phaínesthai to appear) + es adj. suffix] *… …   Universalium

  • allophane — noun An amorphous hydrous aluminium silicate clay mineral …   Wiktionary

  • allophane — (al lo fa n ) s. f. Terme de minéralogie. Variété d argile …   Dictionnaire de la Langue Française d'Émile Littré

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