Apophyllite-(KF)
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameApophyllite-(KF)
Chemical FormulaKCa₄(Si₈O₂₀)(F,OH)·8H₂O
Mohs Hardness4.5
Crystal Systemtetragonal
Lustervitreous
Streak Colorwhite
Cleavageperfect on {001}
Fractureuneven
Specific Gravity2.35
Colorscolorless, white, pale green
Transparencytransparent
Type LocalityJalgaon District, Maharashtra, India
Mineral GroupPhyllosilicates
Usescollector, decorative
Associated MineralsStilbite-Ca, Heulandite, Scolecite, Calcite
Raritycommon
Description
This specimen showcases large, blocky to tabular, transparent to translucent colorless to pale greenish-white crystals of Apophyllite-(KF), intergrown with smaller, salmon-pink, platy crystals of Stilbite-Ca.
Geological Context
Apophyllite-(KF) and Stilbite-Ca are common secondary minerals found filling vesicles and cavities in basaltic volcanic rocks, typically formed by low-temperature hydrothermal alteration processes.
