Chalcedony (Desert Rose or Botryoidal Chalcedony)

Physical Properties

Hardness: 6.5–7 (Mohs scale); Color: White, milky, or waxy; Luster: Waxy to dull; Crystal structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.64

Formation & Geological History

Formed from the deposition of silica from groundwater in the cavities of volcanic rocks or sedimentary formations. This specimen shows botryoidal (grape-like) or 'desert rose' style growth common in arid environments.

Uses & Applications

Used primarily for lapidary work, jewelry (cabochons), and as a decorative specimen for collectors.

Geological Facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen under a normal microscope. It was highly prized in antiquity for cylinder seals in Mesopotamia.

Field Identification & Locations

Identify by its waxy luster, hardness (it can scratch glass), and lack of visible crystals. Commonly found in desert regions or basaltic volcanic fields. Collectors look for unique petal-like shapes or translucency.

Identified on: 4/19/2026

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