Rock Identifier
Banded Agate (Tumbled) (Silicon Dioxide (SiO2) - Microcrystalline Quartz) — mineral
mineral

Banded Agate (Tumbled)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hardness: 6.5-7 on the Mohs scale. Color: Brown, tan, cream, and white concentric or parallel bands. Luster: Waxy to vitreous when polished. Crystal structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None, fractures with a conchoidal break.

Hardness
6
Color
Brown, tan, cream, and white concentric or parallel bands
Luster
Waxy to vitreous when polished
Identified More mineral
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Physical properties

Hardness: 6.5-7 on the Mohs scale. Color: Brown, tan, cream, and white concentric or parallel bands. Luster: Waxy to vitreous when polished. Crystal structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None, fractures with a conchoidal break.

Formation & geological history

Formed in cavities within volcanic rocks or ancient sedimentary formations where silica-rich fluids deposited successive layers of microcrystalline quartz over time.

Uses & applications

Widely used in lapidary art, jewelry making, tumbled stone collections, and decorative accents due to its distinct, attractive banding.

Geological facts

Agate banding is created by subtle changes in mineral composition and trace elements during the slow crystallization of silica-rich groundwater inside rock pockets.

Field identification & locations

Identify by its characteristic fine parallel or concentric layering, translucent to opaque body, high hardness, and smooth waxy polish. Commonly found worldwide in volcanic host rocks and river gravels.