sedimentary

Agate (Water-Worn)

Cryptocrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Honey-yellow, translucent to opaque; Luster: Waxy to vitreous; Structure: Microcrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6

Hardness: 6
Color: Honey-yellow, translucent to opaque
Luster: Waxy to vitreous

Identified July 13, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Honey-yellow, translucent to opaque; Luster: Waxy to vitreous; Structure: Microcrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6

Formation & geological history

Formed from silica-rich groundwater filling voids (gas bubbles) in volcanic rock or cavities in sedimentary rock. This specific specimen has been smoothed and rounded by river or tidal action over thousands of years.

Uses & applications

Used for jewelry (lapidary), decorative ornaments, collection, and historically for burnishing tools or mortar and pestles due to its hardness.

Geological facts

This specimen exhibits a 'crazed' or frosted surface texture common in river agates or sea glass, which results from long-term exposure to water and varying temperatures. Agates are the state rock of many locations including Oregon, Minnesota, and Kentucky.

Field identification & locations

Identify in the field by checking for translucency (candling with a flashlight) and search for the characteristic 'waxy' texture. Commonly found in riverbeds, gravel bars, and coastlines near volcanic regions.