Analcime
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameAnalcime
Chemical FormulaNa(AlSi2O6)·H2O
Mohs Hardness5
Crystal Systemcubic
Lustervitreous
Streak Colorwhite
Cleavagepoor on {100}
Fractureuneven to conchoidal
Specific Gravity2.25
Colorswhite, colorless, gray, yellowish, reddish, greenish
Transparencytransparent to translucent
Type LocalitySiusi Alp (Seis Alp), Gardena Valley (Gröden Valley), Bolzano Province (South Tyrol), Trentino-Alto Adige/Südtirol, Italy
Mineral GroupZeolites (Tectosilicates)
Usescollector, minor industrial uses
Associated Mineralsother zeolites, calcite, prehnite, apophyllite, quartz
Raritycommon
Description
The image displays a cluster of well-formed, white to colorless analcime crystals, typically exhibiting a trapezohedral habit with a distinct vitreous luster.
Geological Context
Analcime is a common zeolite mineral that forms in the vesicles and amygdules of basaltic and other mafic igneous rocks, often as a late-stage hydrothermal alteration product. It can also be found in some sedimentary rocks and low-grade metamorphic environments.
