mineral

Botryoidal Chalcedony (Desert Rose / Grape Agate variant)

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on the Mohs scale. Color: Grayish-blue to muted green. Luster: Waxy to dull. Crystal structure: Cryptocrystalline (hexagonal/trigonal). Form: Botryoidal (grape-like) clusters. Specific Gravity: 2.6–2.64.

Hardness: 6
Color: Grayish-blue to muted green
Luster: Waxy to dull

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in cavities or volcanic vesicles. As the water evaporates or cools, the silica precipitates in spherical layers. These can range from modern formations to millions of years old, often found in arid and volcanic regions.

Uses & applications

Primarily used as decorative display specimens, collector items, and in metaphysical jewelry. While chalcedony is used in industrial abrasives, botryoidal specimens are usually kept intact for their aesthetic value.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning 'a bunch of grapes'. This specimen shows a transition between common chalcedony and decorative agate. It is chemically identical to quartz but has a fibrous microstructure.

Field identification & locations

Identify in the field by its distinct 'bumpy' or rounded cluster appearance and high hardness (it will scratch glass). Common locations include Indonesia, Morocco, and the Southwestern United States. Collectors look for high luster and uniform 'grape' size.

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