| Revision as of 15:33, 31 October 2007 editShinkolobwe (talk | contribs)Extended confirmed users, Pending changes reviewers18,768 edits Addition of two categories: Aluminosilicates and Silicate minerals.← Previous edit | Revision as of 08:24, 6 February 2008 edit undoDumZiBoT (talk | contribs)212,289 editsm Bot: Converting bare referencesNext edit → | ||
| Line 1: | Line 1: | ||
| ] | ] | ||
| '''Illite''' is a non-expanding, ]-sized, micaceous mineral. Illite is a ] or layered alumino-silicate. Its structure is constituted by the repetition of Tetrahedron – Octahedron – Tetrahedron (TOT) layer. The interlayer space is mainly occupied by poorly hydrated potassium cations responsible for the absence of swelling. Structurally illite is quite similar to ] or ] with slightly more ], ], ], and water and slightly less tetrahedral ] and interlayer ]. The chemical formula is given as (K,H<sub>3</sub>O)(Al,Mg,Fe)<sub>2</sub>(Si,Al)<sub>4</sub>O<sub>10</sub><ref>http://webmineral.com/data/Illite.shtml</ref>, but there is considerable ion substitution. It occurs as aggregates of small ] grey to white crystals. Due to the small size, positive identification usually requires ] analysis. Illite occurs as an alteration product of muscovite and ] in ] and ] environments. It is common is sediments, soils, and argillaceous ] as well as in some low grade ]. ] in sediments can be differentiated by x-ray analysis. | '''Illite''' is a non-expanding, ]-sized, micaceous mineral. Illite is a ] or layered alumino-silicate. Its structure is constituted by the repetition of Tetrahedron – Octahedron – Tetrahedron (TOT) layer. The interlayer space is mainly occupied by poorly hydrated potassium cations responsible for the absence of swelling. Structurally illite is quite similar to ] or ] with slightly more ], ], ], and water and slightly less tetrahedral ] and interlayer ]. The chemical formula is given as (K,H<sub>3</sub>O)(Al,Mg,Fe)<sub>2</sub>(Si,Al)<sub>4</sub>O<sub>10</sub><ref></ref>, but there is considerable ion substitution. It occurs as aggregates of small ] grey to white crystals. Due to the small size, positive identification usually requires ] analysis. Illite occurs as an alteration product of muscovite and ] in ] and ] environments. It is common is sediments, soils, and argillaceous ] as well as in some low grade ]. ] in sediments can be differentiated by x-ray analysis. | ||
| The cation exchange capacity (CEC) of illite is smaller than that of ] but higher than that of ], typically around 20 – 30 meq/100 g. | The cation exchange capacity (CEC) of illite is smaller than that of ] but higher than that of ], typically around 20 – 30 meq/100 g. | ||
Revision as of 08:24, 6 February 2008
Illite is a non-expanding, clay-sized, micaceous mineral. Illite is a phyllosilicate or layered alumino-silicate. Its structure is constituted by the repetition of Tetrahedron – Octahedron – Tetrahedron (TOT) layer. The interlayer space is mainly occupied by poorly hydrated potassium cations responsible for the absence of swelling. Structurally illite is quite similar to muscovite or sericite with slightly more silicon, magnesium, iron, and water and slightly less tetrahedral aluminium and interlayer potassium. The chemical formula is given as (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10, but there is considerable ion substitution. It occurs as aggregates of small monoclinic grey to white crystals. Due to the small size, positive identification usually requires x-ray diffraction analysis. Illite occurs as an alteration product of muscovite and feldspar in weathering and hydrothermal environments. It is common is sediments, soils, and argillaceous sedimentary rocks as well as in some low grade metamorphic rocks. Glauconite in sediments can be differentiated by x-ray analysis.
The cation exchange capacity (CEC) of illite is smaller than that of smectite but higher than that of kaolinite, typically around 20 – 30 meq/100 g.
Illite was first described for occurrences in the Maquoketa shale in Calhoun County, Illinois, USA, in 1937. The name was derived from its type location in Illinois. Illite is also called hydromica or hydromuscovite. Brammallite is a sodium rich analogue.
Illite is also used in food supplements, with claimed benefits that range from bowel function to reduction of heavy metals in the blood. Apparently, a French company, Argiletz, provides a wide range of products which are offered for sale in the UK and elsewhere. "Green clay", a term used in several languages, often contains illite. In Scotland, internal uses of illite probably date back to Celtic times.
References
- Mitchell J.K. (1993) Fundamentals of soil behavior. Second edition. John Wiley and Sons, Inc., New York. 437 pp, see Chapter 3, Soil Mineralogy, p. 32.