Apophyllite
Fluorapophyllite-(K) · Collector Mineral / Mineral Specimen
Crystal System
Tetragonal; typically occurs as dipyramids, pseudo-cubic prisms, or in massive/granular clusters. This specimen shows a drusy/granular habit with distinct basal cleavage faces.
Mineral Group
Silicates; Phyllosilicate (Sheet silicate)
Chemical Formula
KCa4Si8O20(F,OH)·8H2O
Formation Process
Commonly forms as a secondary mineral in amygdules or cavities of basalt and other volcanic rocks via hydrothermal deposition from low-temperature aqueous solutions.
About This Crystal
This specimen is a cluster of transparent to translucent colorless crystals. It displays a vitreous to pearly luster, particularly on the prominent flat cleavage face visible at the top. The structure is an aggregate of smaller, intergrown crystals with typical step-like growth.
Physical Characteristics
Color: Colorless to white; Streak: White; Cleavage: Perfect basal {001}; Fracture: Uneven to subconchoidal; Specific Gravity: 2.3–2.4; Tenacity: Brittle; Fluorescence: May show weak yellow or green under UV light.
Optical Properties
Refractive Index: 1.530–1.536; Birefringence: Weak (0.002); Optical Character: Uniaxial (+) or (-); some specimens show anomalous 'fried-egg' interference colors under cross-polarized light.
Hardness & Durability
Origin Region
Notably from the Deccan Traps, India (e.g., Jalgaon, Pune, Nashik); also found in Germany, Brazil, and the USA.
Hardness & Durability
Mohs Hardness: 4.5 to 5. It is relatively soft and brittle with perfect cleavage, making it unsuitable for most jewelry applications and prone to chipping.
Care & Maintenance
Clean with room-temperature soapy water; avoid ultrasonic and steam cleaners. Apophyllite contains water in its structure and can dehydrate if exposed to high heat or long-term direct sunlight. Store separately to prevent scratching.
Rarity & Value
Common in mineral shops but high-quality, large, or unusually colored (green) clusters can be moderately valuable. Typically valued based on crystal clarity and aesthetic cluster formation.
Special Characteristics
Features a very characteristic pearly luster on its basal cleavage planes. Often found in association with zeolites like Stillbite, Heulandite, or Scolecite.
Lore & History
Historically used as a collector mineral due to its high luster. In metaphysical traditions, it is often associated with 'clarity of thought', the crown chakra, and 'high-vibration' spiritual communication, though these are cultural beliefs rather than scientific facts.