mineral
Chalcedony (Yellow Chert / Agate)
Quartz (Silicon Dioxide - SiO2)
AI-generated identification · may be incorrectHardness of 6.5-7 on Mohs scale, waxy to vitreous luster, translucent yellowish-brown to amber color, microcrystalline (cryptocrystalline) structure, conchoidal fracture.
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Physical properties
Hardness of 6.5-7 on Mohs scale, waxy to vitreous luster, translucent yellowish-brown to amber color, microcrystalline (cryptocrystalline) structure, conchoidal fracture.
Formation & geological history
Forms by precipitation of silica from aqueous solutions, commonly in volcanic cavities or sedimentary gravel deposits as stream-rounded nodules.
Uses & applications
Used for lapidary arts, beads, carvings, tumbled gemstones, and ornamental collections.
Geological facts
Cryptocrystalline quartz varieties like chalcedony and agate have been used since prehistoric times for making tools, arrowheads, and jewelry due to their durability and sharp conchoidal fracture.
Field identification & locations
Identified in the field by its smooth, waxy surface, light translucency when held to the sun, absence of cleavage, and resistance to steel scratching. Widely found in river beds, gravel deposits, and alluvial fields.
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