mineral

White Chalcedony (likely Common Opal or Milky Quartz)

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 (Mohs scale); Color: Milky white to translucent grey; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Milky white to translucent grey
Luster: Waxy to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich hydrothermal fluids in volcanic or sedimentary rock cavities. It can also form during the weathering of silicate-rich minerals in arid environments.

Uses & applications

Used in the making of jewelry (beads, cabochons), as ornamental stones, and historically for making sharp tools like arrowheads due to its conchoidal fracture.

Geological facts

Chalcedony is a broad term that includes agate, jasper, and carnelian. White chalcedony is often called 'White Pigeon' or 'Moonlight' chalcedony in the gem trade. High-quality specimens can show an adularescence-like sheen.

Field identification & locations

Identify in the field by its waxy luster and smooth, shell-like fracture surfaces. It cannot be scratched by a steel knife. It is commonly found in basaltic lava flows and desert regions like the American Southwest, Brazil, and India.

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