mineral

Chalcedony (Variety: Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Honey yellow to translucent brown; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Honey yellow to translucent brown
Luster: Waxy to vitreous

Identified July 5, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Honey yellow to translucent brown; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic rocks or sedimentary formations. This specimen appears water-worn, likely from a river or beach environment.

Uses & applications

Used primarily in lapidary work, jewelry (beads, cabochons), and as a collector's specimen. Historically used for making tools due to its sharp fracture edges.

Geological facts

Agate and chalcedony have been used for thousands of years; early humans used them for cylinder seals and amulets. The translucent 'honey' color is often caused by trace amounts of iron oxides.

Field identification & locations

Identify by its waxy luster, translucency when held to light, and lack of visible crystals. It is commonly found in gravel beds, shorelines, and desert washes.