Analcime or analcite (from the Greek analkimos - "weak") is a white, gray, or colorless tectosilicate mineral aluminium form. Its chemical formula Si. Minor amounts of potassium 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. It also occurs as cavity and vesicle fillings associated with prehnite , calcite, and zeolites.