mineral

Botryoidal Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Tan, beige, or white; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.6-2.65

Hardness: 6
Color: Tan, beige, or white
Luster: Waxy to dull

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Tan, beige, or white; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.6-2.65

Formation & geological history

Formed by the precipitation of silica from groundwater in cavities of volcanic or sedimentary rocks. The botryoidal (grape-like) texture occurs as crystals grow outward from multiple centers.

Uses & applications

Used for lapidary work, jewelry (cabochons), and as ornamental display specimens for collectors.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes. This specific specimen has a flesh-like appearance often referred to as 'desert roses' or 'brain agate' when found in specific regions.

Field identification & locations

Identify by its waxy luster, rounded bubble-like surface, and its ability to scratch glass. Commonly found in desert environments or within volcanic geodes.