Analcime

Analcime
Analcime with aegirine and natrolite from Mont Saint-Hilaire, Québec (size: 78 x 65 x 53 mm)
General
Category Zeolite
Formula
(repeating unit)		 NaAlSi2O6·H2O
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 [1]

Analcime or analcite (from the Greek analkimos - "weak") 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

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 in Canada; and in Iceland,and now in Namibia.

See also

References

  • 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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