mineral

Chalcedony on Matrix (Botryoidal Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: White to bluish-white; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Microcrystalline); Cleavage: None; Structure: Botryoidal (grape-like) habit.

Hardness: 6
Color: White to bluish-white
Luster: Waxy to vitreous

Identified June 19, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: White to bluish-white; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (Microcrystalline); Cleavage: None; Structure: Botryoidal (grape-like) habit.

Formation & geological history

Formed by the precipitation of silica from groundwater in the cavities of volcanic rocks (likely andesite or basalt host). It typically forms at low temperatures in the final stages of hydrothermal activity.

Uses & applications

Used as a gemstone for jewelry, carvings, and lapidary art. Highly valued by mineral collectors for its unique bubbling textures.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes. Chalcedony is technically a microcrystalline variety of quartz and can glow under UV light if trace elements are present.

Field identification & locations

Identify by its waxy luster, hardness (it will scratch glass), and the rounded, bubbly surface. Commonly found in volcanic regions, notably Arizona, Oregon, Mexico, and Brazil.

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