Analcime

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Analcime
Analcime, Aegirine, Natrolite-225835.jpg
Analcime with aegirine and natrolite from Mont Saint-Hilaire, Québec (size: 78 x 65 x 53 mm)
General
CategoryZeolite
Formula
(repeating unit)
NaAlSi2O6·H2O
Strunz classification9.GB.05
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupIbca
Identification
ColorWhite, colorless, gray, pink, greenish, yellowish
Crystal habitTypically in crystals, usually trapezohedrons, also massive to granular.
TwinningPolysynthetic on [001], [110]
CleavageVery poor [100]
FractureUneven to subconchoidal
Mohs scale hardness5 - 5.5
LusterVitreous
StreakWhite
Specific gravity2.24 - 2.29
Optical propertiesIsotropic; anomalously biaxial (-)
Refractive indexn = 1.479 - 1.493
Fusibility3.5
Other characteristicsWeakly 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[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 in Canada; and in Iceland,and now in Namibia.

See also[edit]

References[edit]

  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
  • Mineral Galleries
  • Mindat.org
  • Webmineral.com

External links[edit]