Apophyllite (Fluorapophyllite-(K))
Fluorapophyllite-(K) · Mineral Specimen / Collector Mineral
Crystal System
Tetragonal system; common habits include dipyramidal, tabular, and prismatic crystals, often found in radiating clusters or druzy crusts.
Mineral Group
Silicates (Phyllosilicates subgroup)
Chemical Formula
KCa4(Si8O20)F·8H2O
Formation Process
Hydrothermal; it typically forms as a secondary mineral in the cavities (vugs) of basaltic or volcanic rocks from cooling hydrothermal fluids.
About This Crystal
White to colorless translucent cluster with a pearly to vitreous luster. This specimen exhibits a 'sugary' or druzy texture consisting of numerous small interlocking crystals, showing a characteristic pearly sheen on the cleavage planes.
Physical Characteristics
Color: White/Colorless; Streak: White; Cleavage: Perfect basal {001}; Fracture: Uneven to subconchoidal; Specific Gravity: 2.3–2.4; Fluorescence: Frequently pale yellow or green under shortwave UV.
Optical Properties
Refractive Index: 1.530–1.536; Uniaxial (+); unique for its 'anomalous birefringence' which can show beautiful interference colors under polarized light.
Hardness & Durability
Origin Region
The most famous and prolific source is the Deccan Traps in Maharashtra, India (Jalgaon, Pune, Nashik). Also found in Brazil, Mexico, and Germany.
Hardness & Durability
Mohs hardness: 4.5 to 5. It is relatively brittle and sensitive to pressure; toughness is poor due to perfect basal cleavage.
Care & Maintenance
Clean only with lukewarm soapy water; avoid ultrasonic or steam cleaners. It is sensitive to heat, which can cause dehydration and loss of luster. Store separately to prevent scratching.
Rarity & Value
Common mineral in basaltic regions; high-quality green or large clear specimens are more valuable. This white druzy form is an affordable, classic collector's piece.
Special Characteristics
Displays a distinct pearly luster on its basal cleavage face and can contain 'enhydro' water bubbles in rare cases. High water content makes it sensitive to dehydration.
Lore & History
Commonly known in metaphysical circles as the 'Stone of Truth' and associated with the Crown Chakra. Historically significant to mineralogy for its unique phyllosilicate structure that contains both fluorine and water.