mineral

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Hardness: 6.5–7 on the Mohs scale; Color: Translucent white/grey with reddish-brown (Iron oxide) bands; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64.

Hardness: 6
Color: Translucent white/grey with reddish-brown (Iron oxide) bands
Luster: Vitreous to waxy

Identified March 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed by the deposition of silica from groundwater in the cavities (vesicles) of volcanic igneous rocks or sedimentary formations. The bands represent different stages of mineral deposition over thousands of years.

Uses & applications

Commonly used in jewelry (pendants, cabochons), lapidary art, and metaphysical collecting. Historically used for making precision bearings and mortars/pestles due to its hardness and chemical resistance.

Geological facts

Agate was named by the Greek philosopher Theophrastus, who discovered the stone along the shores of the Achates River in Sicily. It is one of the oldest gemstones used in human history, dating back to the Neolithic era.

Field identification & locations

Identify in the field by its distinct concentric banding, translucent edges, and 'waxy' texture compared to surrounding host rock. Commonly found in basaltic lava flows in Brazil, Uruguay, and the Lake Superior region of the USA. Tips: Look for nodules with a rough, pitted exterior and glowing translucence when held to light.

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