mineral

Chalcedony with inclusions (Agate/Quartz)

Silicon Dioxide (SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Translucent grayish-blue with yellow/brown inclusions; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.60–2.64.

Hardness: 6
Color: Translucent grayish-blue with yellow/brown inclusions
Luster: Waxy to vitreous

Identified March 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed at low temperatures through the deposition of silica-rich groundwater in cavities of igneous or sedimentary rocks. It common develops in volcanic vesicles or limestone fissures over millions of years.

Uses & applications

Used primarily in lapidary arts for cabochons, beads, and carvings. Also used in precision tools for grinding due to its hardness and stability.

Geological facts

Chalcedony has been used since the Bronze Age for seals and jewelry because it does not stick to hot wax. The specific yellow inclusions in this specimen are likely iron oxides like limonite or goethite trapped within the quartz matrix.

Field identification & locations

Identify in the field by its waxy appearance, lack of graininess, and ability to scratch glass. This specimen appears water-worn (tumbled), likely found in a riverbed or coastal area. Common in volcanic regions globally.

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