mineral

Botryoidal Chalcedony (Agate/Desert Rose Chalcedony)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7 (Mohs scale); Color: White, translucent grey, to tan; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: White, translucent grey, to tan
Luster: Waxy to vitreous

Identified February 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the low-temperature deposition of silica-rich groundwater in cavities of igneous or sedimentary rocks. This specific botryoidal (grape-like) habit indicates slow growth in an open void or pocket.

Uses & applications

Used primarily for lapidary work (cabochons), jewelry making, display as mineral specimens, and sometimes used in industrial abrasives.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without extreme magnification. The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes.

Field identification & locations

Identify in the field by its characteristic 'bubbly' or rounded surface and waxy appearance. It cannot be scratched by a steel knife. Common in volcanic regions and arid desert environments like the Southwestern US, Morocco, and Brazil.

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