mineral
Chalcedony (Yellow Agate / Carnelian Chalcedony)
Silicon Dioxide (SiO2)
Hardness 6.5-7 on the Mohs scale, translucent to waxy luster, yellow to pale amber microcrystalline quartz structure, conchoidal fracture, specific gravity ~2.6.
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Physical properties
Hardness 6.5-7 on the Mohs scale, translucent to waxy luster, yellow to pale amber microcrystalline quartz structure, conchoidal fracture, specific gravity ~2.6.
Formation & geological history
Formed in low-temperature silica-rich hydrothermal fluids filling cavities or fractures within volcanic or sedimentary rocks, creating distinct fibrous layering.
Uses & applications
Used in lapidary work, jewelry, tumbling, decorative stone carvings, and rock collecting.
Geological facts
Chalcedony is composed of microscopic intergrowths of quartz and moganite. The translucent yellow banding seen here is characteristic of seam agate or agate veinlets.
Field identification & locations
Identified by its waxy luster, hardness (will scratch glass), translucent layer banding, and lack of distinct cleavage. Commonly found in gravel beds, desert rockhounding sites, and volcanic terrains globally.
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