mineral
Yellow Chalcedony (Agate/Carnelian)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Pale yellow to honey-gold, Luster: Waxy to vitreous, Crystal Structure: Trigonal/Microcrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.64
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Pale yellow to honey-gold, Luster: Waxy to vitreous, Crystal Structure: Trigonal/Microcrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.64
Formation & geological history
Forms from the deposition of silica from groundwater in hydrothermal environments or sedimentary cavities. Often found as nodules in volcanic rocks or as water-worn pebbles in riverbeds.
Uses & applications
Used primarily for lapidary work, decorative cabochons, jewelry, and metaphysical collecting. Historically used for making tools due to its hardness and sharp fracture edges.
Geological facts
Yellow chalcedony is often classified as a variety of agate when it shows banding, or light carnelian. It is the microcrystalline relative of amethyst and citrine.
Field identification & locations
Identify by its waxy luster, translucency, and inability to be scratched by a steel knife. Commonly found in Brazil, India, Uruguay, and the western United States. Look for smooth, rounded surfaces on weathered pieces.
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