mineral

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 on Mohs scale; Color: Translucent white to light gray; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Microcrystalline); Cleavage: None; Specific Gravity: 2.58 - 2.64

Hardness: 6
Color: Translucent white to light gray
Luster: Waxy to vitreous

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in the cavities of volcanic or sedimentary rocks. This specific specimen shows a 'botryoidal' (grape-like) habit common in late-stage hydrothermal deposition.

Uses & applications

Used primarily in lapidary arts for jewelry, cabochons, and ornamental carvings. It also has historical significance in seal-making due to its hardness and lack of cleavage.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are so small they can only be seen under extreme magnification. It has been used for tool-making since the Bronze Age.

Field identification & locations

Identify in the field by its waxy luster, smooth rounded surfaces (if botryoidal), and its ability to scratch glass. Commonly found in desert regions, riverbeds, and volcanic geodes worldwide.