gemstone

Blue Agate

Chalcedony (SiO2)

Hardness: 6.5 to 7 on the Mohs scale. Color: Shades of blue, white, and translucent gray with distinct banding. Luster: Waxy to vitreous. Crystal structure: Trigonal (microcrystalline quartz). Cleavage: None. Specific gravity: 2.58 to 2.64.

Hardness: 6
Luster: Waxy to vitreous

Identified August 2, 2026More gemstone →

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Physical properties

Formation & geological history

Forms primarily within cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions layer by layer over millions of years.

Uses & applications

Widely used in jewelry making, ornamental carvings, polished display pieces, and as a popular stone for lapidary arts and crystal collecting.

Geological facts

Agate has been prized by ancient civilizations since Neolithic times, used for amulets, seals, and decorative vessels due to its durability and striking banded patterns.

Field identification & locations

Easily identified by its characteristic curved or parallel color banding and waxy luster on tumbled or polished surfaces. Commonly found worldwide, notably in Brazil, India, Madagascar, and the United States.