mineral

Banded Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Swirls of grey, blue, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Swirls of grey, blue, and white
Luster: Vitreous to waxy

Identified April 9, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Swirls of grey, blue, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed primarily within volcanic and metamorphic rocks. It occurs as a result of silica-rich groundwater filling cavities or vesicles in cooling lava, depositing layers of microcrystalline quartz over time.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative carvings, precision pendulums, and as a collector's stone. Historically used for making mortars and pestles due to its hardness.

Geological facts

The banding in agate is caused by the periodic precipitation of silica. Each layer represents a different pulse of mineral-rich fluids entering the cavity. It is often associated with the 'Eye of God' in various ancient cultures.

Field identification & locations

Identified by its waxy luster, rhythmic banding, and translucency when held to light. Found globally in areas with ancient volcanic activity, notably Brazil, India, and the Lake Superior region of the US.