Chalcedony in Matrix
Quartz var. Chalcedony · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal/Monoclinic; Microcrystalline (cryptocrystalline) aggregate with massive, vein-filling habit
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with trace inclusions
Formation Process
Hydrothermal; formed as silica-rich fluids deposit in fractures and vesicles of volcanic host rock (basalt) at low temperatures.
About This Crystal
Translucent to semi-opaque light blue-grey vein of chalcedony embedded in a dark, porous basaltic matrix. It exhibits a waxy to vitreous luster and a smooth, botryoidal-leaning texture within the vein.
Physical Characteristics
Color: Bluish-white vein, dark grey matrix; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Weak green or white under UV.
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Up to 0.004; Optical Sign: Uniaxial (+); Phenomena: Tyndall scattering (blue tint).
Hardness & Durability
Origin Region
Found globally; notably Brazil, USA (Oregon/Arizona), and Iceland. Often located in volcanic basalt cavities.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: High (due to fibrous structure); Very durable for jewelry, though matrix may be softer.
Care & Maintenance
Clean with warm soapy water and soft brush; avoid hydrofluoric acid; safe for ultrasonic cleaners unless matrix is crumbly.
Rarity & Value
Common; Value is determined by color saturation and pattern. Roughly $2-$10 for a raw specimen of this size.
Special Characteristics
Microcrystalline fibrous structure; exhibits translucency in thin sections; contains natural porous host rock (matrix) inclusions.
Lore & History
Historically used for seals and cameos in Ancient Greece and Rome. Traditionally associated with the throat chakra and believed to promote stability and calm communication.