mineral

Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: White, grey, light blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.58-2.64

Hardness: 6
Color: White, grey, light blue
Luster: Waxy to vitreous

Identified June 20, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: White, grey, light blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); 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 shows a druzy crystalline interior and a cryptocrystalline outer layer.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), and as a collector's mineral specimen. Some industrial use as an abrasive.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without high magnification. It often forms the base of agates and geodes.

Field identification & locations

Identify by its waxy luster, conchoidal fracture, and hardness (it will scratch glass). Often found in desert regions or areas with ancient volcanic activity.