Fluorapophyllite-(K)
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameFluorapophyllite-(K)
Chemical FormulaKCa₄(Si₈O₂₀)F·8H₂O
Mohs Hardness4.5
Crystal Systemtetragonal
Lustervitreous
Streak Colorwhite
Cleavageperfect on {001}
Fractureuneven to conchoidal
Specific Gravity2.35
Colorswhite, colorless
Transparencytransparent to translucent
Type LocalityPandulena Hill, Nasik District, Maharashtra, India
Mineral GroupPhyllosilicates
Usescollector's specimens
Associated MineralsStilbite, Heulandite, Scolecite, Calcite
Raritycommon
Description
A large specimen featuring numerous clear to milky white, blocky to tabular crystals of fluorapophyllite-(K) intergrown with smaller, peach-colored stilbite crystals.
Geological Context
Fluorapophyllite-(K) typically forms in the vesicles and cavities of basaltic volcanic rocks, often associated with zeolites, as a late-stage hydrothermal alteration product. The Deccan Traps in India are famous for such occurrences.
