mineral

Chalcedony (Agate Pebble)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Pale orange to cream; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Pale orange to cream
Luster: Waxy to vitreous

Identified July 9, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Pale orange to cream; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic or sedimentary rocks. This specimen has been naturally tumbled and rounded by water transport in a river or beach environment.

Uses & applications

Used primarily in lapidary arts, jewelry (beads, cabochons), and as decorative aquarium or garden stones. Historically used for making stone tools due to its conchoidal fracture.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without high magnification. When it shows banding, it is called Agate; when it is translucent orange/red, it is called Carnelian.

Field identification & locations

Identify in the field by its translucency (hold it to the light), waxy texture, and extreme hardness (it will scratch glass). Commonly found on gravel bars, beaches, and in dry wash beds.