Stilbite on Quartz/Matrix
Stilbite (IMA-approved name encompassing stilbite-Ca and stilbite-Na series) · Mineral Specimen and Collector Mineral
Crystal System
Monoclinic system, typically forming sheaf-like aggregates, bundles, or parallel groupings of tabular crystals, often resembling bow-ties.
Mineral Group
Silicates, specifically the Tectosilicate subgroup belonging to the Zeolite group.
Chemical Formula
NaCa4(Si27Al9)O72·n(H2O)
Formation Process
Hydrothermal and low-temperature secondary alteration processes. Zeolites like stilbite typically crystallize from hot, mineral-rich alkaline solutions circulating through vesicles and cavities in basaltic lavas.
About This Crystal
The specimen features characteristic salmon-pink to peach-colored, sheaf-like or bow-tie crystal aggregates of stilbite resting upon a grayish-green matrix or quartz/celadonite coating. The individual stilbite crystals display a translucent to transparent nature with a pearly to vitreous luster on cleavage planes.
Physical Characteristics
Color ranges from colorless, white, yellow, to distinct salmon-pink or peach. Streak is white. Cleavage is perfect on {010}. Fracture is uneven to conchoidal. Specific gravity is approximately 2.1 to 2.2. Tenacity is brittle. May show weak fluorescence under UV light depending on trace impurities.
Optical Properties
Biaxial (-) with refractive indices around n_alpha = 1.484 - 1.490, n_beta = 1.488 - 1.494, n_gamma = 1.490 - 1.496. Birefringence is low (0.004 to 0.006). Pleochroism is typically weak or absent.
Hardness & Durability
Origin Region
Notable global sources include the Deccan Traps in India, Iceland, the Faroe Islands, the USA (New Jersey, Oregon), and various locations in Nova Scotia, Canada. They primarily form in cavities of basaltic and volcanic rocks.
Hardness & Durability
Mohs hardness is 3.5 to 4. Poor durability for general jewelry due to low hardness and perfect cleavage. Easily scratched by a knife or quartz.
Care & Maintenance
Extremely sensitive to sudden temperature changes (thermal shock) and acids. Clean gently with warm soapy water using a soft brush. Avoid ultrasonic cleaners, steam cleaning, and harsh chemicals. Store away from harder minerals to prevent scratching.
Rarity & Value
Common to uncommon as mineral specimens, though fine aesthetic bow-tie groupings from classic localities like India can command moderate collector value. Value depends on crystal size, color intensity, damage-free condition, and contrast with the matrix.
Special Characteristics
Forms distinctive 'bow-tie' or sheaf-like crystal aggregates. Possesses zeolitic water, meaning it can reversibly lose and absorb water molecules within its crystal structure without altering the framework.
Lore & History
Often associated in metaphysical practices with opening the heart chakra, emotional healing, and bringing a gentle, calming energy. These are traditional belief systems and cultural symbolisms rather than scientifically proven properties.