analcimi

Analcime is a mineral belonging to the zeolite group, characterized by its chemical formula (Na,K)AlSi2O6·H2O. It is a tectosilicate, meaning its structure is based on a framework of interconnected SiO4 and AlO4 tetrahedra. The framework is a three-dimensional network of eight-membered rings of silica and alumina tetrahedra, which creates cavities where water molecules and cations, primarily sodium and potassium, are loosely held. Analcime typically crystallizes in the isometric system, often forming trapezohedral crystals, though massive and granular forms are also common.

Its color can range from colorless to white, gray, or yellowish. Analcime is a relatively soft mineral, with a Mohs hardness of 5 to 5.5, and it has a vitreous to greasy luster. It is found in a variety of geological settings, including igneous rocks such as basalts and andesites, often as a secondary mineral in vesicles or amygdules. It can also occur in sedimentary rocks and as a hydrothermal alteration product. Analcime is not a particularly economically significant mineral, but it is of interest to mineralogists for its structural characteristics and its presence in various rock types. It is a common mineral in alkaline volcanic rocks.