Blue Agate

Physical Properties

Hardness: 6.5-7.0 (Mohs scale); Color: Banded shades of blue, grey, and white; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58-2.64

Formation & Geological History

Formed in cavities of volcanic rocks or ancient lavas. Silica-rich groundwater percolates through vesicles, depositing layers of microcrystalline quartz (chalcedony) over thousands of years. Often found in Cenozoic era basaltic flows.

Uses & Applications

Used extensively in jewelry (cabochons, beads), decorative carvings, high-precision pendulums, mortar and pestles for chemical work due to its hardness, and as collector specimens.

Geological Facts

The banding in agates is often rhythmic and can represent seasonal or chemical variations in the mineral-rich water at the time of formation. Blue Lace Agate is a specific variety highly prized for its delicate, wavy patterns.

Field Identification & Locations

Identify by looking for distinct concentric or parallel banding and a waxy texture. Commonly found in Brazil, Uruguay, and parts of the United States like Oregon and the Lake Superior region. Translucency is a key identifier when held to light.

Identified on: 4/22/2026

Mode: Standard