Banded Agate

Physical Properties

Hardness: 6.5–7 on Mohs scale; Color: Multi-colored bands (brown, white, grey, orange); Luster: Waxy to vitreous; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Formation & Geological History

Formed primarily within volcanic and metamorphic rocks. Agates develop in cavities (vesicles) from the deposition of silica from groundwater that contains dissolved minerals. The banding occurs due to rhythmic crystallization changes over thousands of years.

Uses & Applications

Commonly used in jewelry (cabochons, beads), decorative carvings, and as a collector's specimen. Due to its hardness, it is also used in precision pendulums and laboratory mortars and pestles.

Geological Facts

Agate was named by Theophrastus, a Greek philosopher, who discovered the stone along the shore line of the river Achates in present-day Sicily. Each agate specimen is unique and records the specific chemical history of the cavity it formed in.

Field Identification & Locations

Identify in the field by its distinct concentric or parallel banding, waxy texture when broken, and translucency when held up to light. It is commonly found in river beds, beaches, and areas with ancient volcanic activity.

Identified on: 4/18/2026

Mode: Standard