mineral

Chalcedony (Quartz Pebble)

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 Mohs; Color: Translucent grayish-tan with cloudy white inclusions; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture.

Hardness: 6
Color: Translucent grayish-tan with cloudy white inclusions
Luster: Waxy to vitreous

Identified June 26, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Translucent grayish-tan with cloudy white inclusions; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture.

Formation & geological history

Formed from the deposition of silica from aqueous solutions, often in volcanic or sedimentary environments. This specimen is water-worn, suggesting transport via river or coastal activity.

Uses & applications

Used for semi-precious jewelry, lapidary art (tumbling), and historically for tool making (flint knapping).

Geological facts

Chalcedony is formed by microscopic crystals of quartz and moganite. Its name is derived from the ancient Greek town of Chalcedon in Asia Minor.

Field identification & locations

Identify by its characteristic waxy luster and translucency when held to light. Found globally in gravel beds, shorelines, and basaltic regions.

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