Analcite

From Wikipedia, the free encyclopedia

Analcite

General
Category	Mineral
Chemical formula	NaAlSi₂O₆·H₂O
Identification
Color	Colorless to white
Crystal habit	Typically in crystals, usually trpezohedrons, also massive to granular.
Crystal system	Isometric; 4/m bar 3 2/m
Cleavage	Absent
Fracture	Uneven
Mohs Scale hardness	5 - 5.5
Luster	Vitreous
Refractive index	nα=1.479 - 1.493 nγ=1.480 - 1.494
Streak	white
Specific gravity	2.27
Fusibility	3.5

Analcite or analcime (from the Greek analkimos - "weak") is a white, grey, or colourless tectosilicate mineral. Analcite consists of hydrated sodium aluminium silicate in cubic crystalline form. Its chemical formula is NaAlSi₂O₆·H₂O. Minor potassium and calcium substitute for sodium. A silver bearing synthetic variety also exists (Ag-analcite).

Analcite is usually classified as a zeolite mineral, but structurally and chemically it is more similar to the feldspathoids. Analcite occurs as a primary mineral in analcme basalt and other alkaline igneous rocks. 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 in the United States; and at Cape Blomidon, Nova Scotia and Mont Saint-Hilaire, Quebec in Canada; and in Iceland.