Blue Chalcedony
Quartz var. Chalcedony · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal/Monoclinic; Microcrystalline or Cryptocrystalline. Typically occurs in botryoidal, massive, or nodular habits.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with trace amounts of nickel, iron, or chromium impacting color
Formation Process
Hydrothermal/Sedimentary; forms via the deposition of silica from aqueous solutions in rock cavities at relatively low temperatures.
About This Crystal
A translucent to opaque microcrystalline quartz. This specimen shows a waxy to vitreous luster with a grayish-blue body color and a rough, rocky matrix involving iron-oxide staining.
Physical Characteristics
Color: Pale blue to bluish-gray; Streak: White; Cleavage: None; Fracture: Conchoidal to splintery; Specific Gravity: 2.6-2.64; Fluorescence: Often inert but can show weak green or blue under UV.
Optical Properties
Refractive Index: 1.530–1.544; Double Refraction: Aggregates are typically SR; Pleochroism: none; Luster: Waxy to dull in raw form.
Hardness & Durability
Origin Region
Notable sources include Turkey, Namibia, Malawi, and the United States (Oregon/Nevada). Often found in volcanic cavities and sedimentary rock.
Hardness & Durability
Mohs Hardness: 6.5 - 7; Toughness: Very High (due to fibrous structure); Excellent durability for jewelry.
Care & Maintenance
Clean with warm soapy water and a soft brush. Generally stable, but avoid harsh chemicals and prolonged exposure to high heat which may alter color.
Rarity & Value
Common to Uncommon. High-quality 'Holley Blue' or 'Turkish Blue' varieties command higher prices. Value is determined by color intensity and translucency.
Special Characteristics
Can exhibit a soft glow or adularescence-like quality when polished. Microscopic fibrous structure provides extreme resistance to chipping.
Lore & History
Historically used in seals and amulets in ancient Greece and Rome. Traditional beliefs associate it with the throat chakra and consider it a 'speaker's stone' for calm communication.