mineral

Chalcedony (Common Opal or Agate variant)

Silicon dioxide (SiO2) with trace hydration

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Pale yellow, translucent to waxy; Luster: Vitreous to waxy; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); SG: 2.6

Hardness: 6
Color: Pale yellow, translucent to waxy
Luster: Vitreous to waxy

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Pale yellow, translucent to waxy; Luster: Vitreous to waxy; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); SG: 2.6

Formation & geological history

Formed via low-temperature deposition of silica-rich groundwater in cavities of volcanic or sedimentary rocks. This specimen appears to be a weathered river or field pebble.

Uses & applications

Used for lapidary work, jewelry (cabochons), and as a collector's specimen. Known as a 'healing stone' in metaphysical circles.

Geological facts

Chalcedony is made of microcrystalline quartz and moganite. When it shows banding it is called agate; when it is translucent and waxy like this, it is often just called chalcedony or common opal.

Field identification & locations

Identify by its waxy luster, conchoidal (shell-like) fracture, and inability to be scratched by a steel knife. Best found in gravel beds or volcanic regions after rain.