12 Photos
Analcime
Chemical Formula	NaAlSi2O6·H2O
Species	Silicates
Crystal System	Triclinic
Mohs Scale	5
Specific Gravity	2.24-2.29
Color	White, colorless, gray, pink, greenish, yellowish
Streak	White
Luster	Vitreous
Refractive Index	n = 1.479 - 1.493 n = 1.480 - 1.494
Diaphaneity	Transparent, Translucent
Cleavage	Poor/Indistincton
Fracture	Sub-Conchoidal
Crystal Habit：Typically in crystals, usually trapezohedrons, also massive to granular.
Geological Setting：In the groundmass or vesicles of silica-poor intermediate and mafic igneous rocks, typically basalts and phonolites, from late-stage hydrothermal solutions, or disseminated due to deuteric alteration. In lake beds, altered from pyroclastics or clays, or as a primary precipitate; authigenic in sandstones and siltstones.

Analcime or analcite (from the Greek analkimos - "weak") is a white, grey, or colourless 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 include 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.