mineral
Chalcedony (Botryoidal or Chalcedony Rose)
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Pale pink to white; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.64
- Hardness
- 6
- Color
- Pale pink to white
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Pale pink to white; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.64
Formation & geological history
Formed from the deposition of silica-rich water in cavities of volcanic rocks or sedimentary environments. The botryoidal (grape-like) habit occurs as silica precipitates around a core or along a surface.
Uses & applications
Used primarily in lapidary arts for carvings and jewelry, as well as a popular specimen for mineral collectors.
Geological facts
This bubbly, rounded growth pattern is called 'botryoidal' from the Greek word for 'bunch of grapes'. Chalcedony is the cryptocrystalline form of quartz, meaning its crystals are too small to see with a standard microscope.
Field identification & locations
Identify by its waxy luster, smooth rounded surfaces, and the fact that it cannot be scratched by a steel knife. Found globally, extensively in the southwestern USA, Brazil, and Namibia.
