mineral

Yellow Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Translucent to opaque yellow. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.6–2.64.

Hardness: 6
Color: Translucent to opaque yellow
Luster: Waxy to vitreous

Identified June 11, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on Mohs scale. Color: Translucent to opaque yellow. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.6–2.64.

Formation & geological history

Formed from silica-rich fluids depositing in cavities or fissures within volcanic or sedimentary rocks at low temperatures. It is found in hydrothermal environments and as a result of chemical weathering.

Uses & applications

Used primarily in lapidary arts for cabochons, beads, and carvings. Historically used for seals, jewelry, and ornamental objects.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen with a regular microscope. Yellow varieties are often colored by iron inclusions (limonite or goethite).

Field identification & locations

Identify by its waxy luster, conchoidal fracture, and lack of cleavage. Found globally, with notable deposits in Brazil, Madagascar, India, and the United States (western states like Oregon and California).