Rhyolite (Rainforest Jasper or Leopard Skin Jasper)
Spherulitic Rhyolite / Quartz var. Rhyolite · Semi-Precious Gemstone / Decorative Stone
Crystal System
Amorphous/Microcrystalline (Trigonal/Monoclinic constituents). Usually massive or spherulitic habit.
Mineral Group
Silicates (Tectosilicates); Volcanic Rock composed of Quartz and Feldspar
Chemical Formula
SiO2 (predominantly) with KAlSi3O8 (Orthoclase) and (Na,Ca)(Al,Si)4O8 (Plagioclase)
Formation Process
Igneous: Formed by the rapid cooling of silica-rich (felsic) lava, often containing gas bubbles (vesicles) later filled by silica precipitation.
About This Crystal
A fine-grained volcanic rock with a varied, mottled appearance. This specimen shows peach-colored spherulites or 'phenocrysts' embedded in a dark green to black glassy/fine-grained groundmass. It has a vitreous to waxy luster and is opaque.
Physical Characteristics
Color: Pink-peach and forest green mottled; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.4 - 2.6; Fluorescence: Generally inert.
Optical Properties
Refractive Index: Approx. 1.54 (aggregate); Birefringence: N/A (rock aggregate); Luster: Vitreous when polished; Transparency: Opaque.
Hardness & Durability
Origin Region
Notably Western Australia, Mexico, and the United States (Utah/Oregon). Formed in volcanic environments.
Hardness & Durability
Mohs Hardness: 6.5 - 7.0. Very durable with high toughness, suitable for all types of jewelry.
Care & Maintenance
Clean with warm soapy water and a soft brush. Resistant to most household chemicals, but avoid prolonged exposure to harsh acids. Store separately from softer stones.
Rarity & Value
Common; Value is generally low to moderate. Factors include pattern vibrancy and polish quality. Carved shapes like this heart are popular in the trade.
Special Characteristics
Features orbicular or spherulitic patterns (peach spots) which are radial clusters of needle-like crystals (usually feldspar or quartz) grown during cooling.
Lore & History
Historically used for tools and weapons due to its toughness. Metaphysically, it is traditionally associated with change, progress, and balance, often linked to the Heart and Solar Plexus chakras in crystal healing lore.