Analcime
| Analcime | |
|---|---|
)window.location='https://en.wikipedia.org/wiki/File:Analcime_-_Kahwan_Mountain,_Semnan,_Iran.jpg') Reddish crystals of analcime up to 1.8 cm in size on matrix | |
| General | |
| Category | Zeolite |
| Formula (repeating unit) | NaAlSi2O6·H2O |
| IMA symbol | Anl[1] |
| Strunz classification | 9.GB.05 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Ibca |
| Identification | |
| Color | White, colorless, gray, pink, greenish, yellowish |
| Crystal habit | Typically in crystals, usually trapezohedrons, also massive to granular. |
| Twinning | Polysynthetic on [001], [110] |
| Cleavage | Very poor [100] |
| Fracture | Uneven to subconchoidal |
| Mohs scale hardness | 5 - 5.5 |
| Luster | Vitreous |
| Streak | White |
| Specific gravity | 2.24 - 2.29 |
| Optical properties | Isotropic; anomalously biaxial (-) |
| Refractive index | n = 1.479 - 1.493 |
| Fusibility | 3.5 |
| Other characteristics | Weakly piezoelectric; weakly electrostatic when rubbed or heated. |
| References | [2] |
Analcime or analcite (from the Greek analkimos - "not strong") is a white, gray, or colorless tectosilicate mineral. Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form. Its chemical formula is NaAlSi2O6·H2O. Minor amounts of potassium and calcium substitute for sodium. A silver-bearing synthetic variety also exists (Ag-analcite).
Analcime is usually classified as a zeolite mineral, but structurally and chemically it is more similar to the feldspathoids. Analcime occurs as a primary mineral in analcime basalt and other alkaline igneous rocks. It also occurs as cavity and vesicle fillings associated with prehnite, calcite, and zeolites.
Locations[edit]
Well known locations for sourcing analcime include Croft Quarry in Leicestershire, UK; the Cyclopean Islands east off Sicily and near Trentino in northern Italy; Victoria in Australia; Kerguelen Island in the Indian Ocean; in the Lake Superior copper district of Michigan, Bergen Hill, New Jersey, Golden, Colorado, and at Searles Lake, California in the United States; and at Cape Blomidon, Nova Scotia and Mont Saint-Hilaire, Quebec[3] in Canada; and in Iceland, and now in Namibia.
Analcime forms in sedimentary rocks at temperatures below about 100 °C (212 °F), and so its presence indicates that the rock has experienced shallow diagenesis.[4]
See also[edit]
- List of minerals – List of minerals for which there are articles on Wikipedia
References[edit]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Handbook of Mineralogy, Mineral Data Publishing
- ^ Normand, Charles; Tarassoff, Peter (2006). Mineralogy and geology of the Poudrette quarry, Mont SaintHilaire, Quebec (PDF). Mineralogical Association of Canada. Retrieved 12 March 2022.
- ^ Prothero, Donald R.; Schwab, Fred (2004). Sedimentary geology : an introduction to sedimentary rocks and stratigraphy (2nd ed.). New York: W.H. Freeman. p. 124. ISBN 0716739054.
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
- Mineral Galleries
- Mindat.org
- Webmineral.com
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