mineral

Chalcedony (Agate / Jasper Specimen)

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 on Mohs scale. Color: Brownish-tan, yellowish, and greenish hues. Luster: Waxy to vitreous. Crystal system: Trigonal (microcrystalline/cryptocrystalline aggregate). Cleavage: None, conchoidal fracture. Specific gravity: 2.58 - 2.64.

Hardness: 6
Color: Brownish-tan, yellowish, and greenish hues
Luster: Waxy to vitreous

Identified July 27, 2026More mineral →

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Physical properties

Formation & geological history

Forms in low-temperature hydrothermal environments, volcanic rocks, and sedimentary beds as silica-rich fluids precipitate into cavities or replace organic materials over millions of years.

Uses & applications

Used in lapidary arts, jewelry, cabochon cutting, decorative carvings, and as collectible rockhound specimens.

Geological facts

Cryptocrystalline quartz varieties like agate and jasper are made of micro-fibrous intergrowths of quartz and moganite, resulting in durable, smooth-fracturing stones.

Field identification & locations

Identify in the field by its hardness (scratches glass), lack of visible crystalline grain with the naked eye, and distinctive waxy luster on fractured surfaces. Common along riverbeds, gravel deposits, and volcanic terrains worldwide.

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