Analcime
Image: Ivar Leidus (CC BY-SA 4.0)
Mineral NameAnalcime
Chemical FormulaNa(AlSi2O6)·H2O
Mohs Hardness5
Crystal Systemcubic
Lustervitreous
Streak Colorwhite
Cleavagepoor on {100}
Fractureuneven to conchoidal
Specific Gravity2.25
Colorscolorless, white, reddish, pink, orange
Transparencytransparent to translucent
Type LocalityKahwan Mountain, Semnan, Iran
Mineral GroupSilicates (Zeolite Group)
Usescollector, industrial
Associated Mineralscalcite, other zeolites, apophyllite
Raritycommon
Description
This specimen displays reddish-orange analcime crystals, up to 1.8 cm, exhibiting a trapezohedral habit, set on a reddish-brown volcanic matrix. Smaller white to pinkish crystals are also present on the matrix.
Geological Context
Analcime commonly forms in the amygdaloidal cavities of basaltic and other volcanic rocks, as well as in hydrothermal veins and some sedimentary environments. It is a typical mineral of the zeolite facies.
