Apophyllite-(KF) with Stilbite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameApophyllite-(KF) with Stilbite
Chemical FormulaApophyllite-(KF): KCa₄(Si₈O₂₀)F·8H₂O; Stilbite: NaCa₂Al₅Si₁₃O₃₆·14H₂O
Mohs Hardness3.5
Streak ColorWhite
CleavagePerfect in one direction (Apophyllite: {001}, Stilbite: {010})
FractureUneven to conchoidal
Specific Gravity2.1
Colorsgreen, white, pale orange
TransparencyTransparent to translucent
Type LocalityNasik quarry, Nasik District, Maharashtra, India
Mineral GroupPhyllosilicates (Apophyllite) and Tectosilicates (Stilbite, a zeolite)
Usescollector
Associated MineralsStilbite, Apophyllite
Rarityuncommon
Description
This specimen features a prominent, blocky, light green apophyllite crystal, exhibiting good transparency and a vitreous luster. It is associated with radiating clusters of pale orange to white stilbite crystals, which have a pearly luster.
Geological Context
These minerals typically form in the vesicles and cavities of basaltic rocks, particularly within the Deccan Traps of India, as a result of late-stage hydrothermal alteration of volcanic rocks.
