sedimentary

Banded Agate

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Gray, white, and smoky brown bands; Luster: Waxy to vitreous; Crystal structure: Hexagonal/Trigonal (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Gray, white, and smoky brown bands
Luster: Waxy to vitreous

Identified July 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in cavities of volcanic or sedimentary rocks through the deposition of silica-rich groundwater. Over long periods, rhythmic crystallization creates the distinct banding patterns shown in this tumbled specimen.

Uses & applications

Commonly used for lapidary work, jewelry making (beads, cabochons), home decor, and as pocket stones for crystal collecting enthusiasts.

Geological facts

Agate is a variety of chalcedony. The name comes from the Achates River in Sicily where agates were first discovered by the ancient Greeks. This specific specimen has been tumbled and polished to reveal its internal banding.

Field identification & locations

Identify in the field by its waxy appearance, conchoidal fracture (smooth, curved glass-like breaks), and characteristic banding. Often found as nodules in dry lake beds or along river currents.