mineral

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Translucent grey to light brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Translucent grey to light brown
Luster: Waxy to vitreous

Identified May 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Translucent grey to light brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic and sedimentary rocks. This specimen is likely a water-worn pebble or a tumbled stone from a geologically recent alluvial deposit.

Uses & applications

Used primarily for jewelry (cabochons, beads), microcrystalline carvings, and as a semi-precious collector's gemstone due to its durability and translucence.

Geological facts

Agate and chalcedony were among the first materials used by early humans for tools because of their conchoidal fracture, similar to flint.

Field identification & locations

Identified in the field by its translucency, waxy surface, and 'orange peel' texture on weathered surfaces. Commonly found in riverbeds, beaches, and volcanic regions like Oregon, Brazil, and India.