Stilbite
Image: Deidre Woollard (CC BY 2.0)
Mineral NameStilbite
Chemical Formula(Ca,Na,K)2-3Al3(Al,Si)2Si13O36·14H2O
Mohs Hardness3.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {010}
Fractureuneven
Specific Gravity2.15
Colorspeach, salmon, white, yellow, brown
Transparencytranslucent
Type LocalityDeccan Traps, India
Mineral GroupZeolites, Tectosilicates
Usescollector
Associated Mineralsapophyllite, heulandite, calcite, quartz
Raritycommon
Description
A prominent peach-colored mineral forming radiating, bladed crystals in a sheaf-like aggregate, often on a dark matrix. Its characteristic habit and color make it a popular collector's specimen.
Geological Context
Stilbite commonly forms in amygdaloidal cavities within basaltic volcanic rocks, as well as in hydrothermal veins and some metamorphic rocks. It is a product of low-temperature alteration of volcanic glass and feldspars.
