mineral

Agate (Yellow Moss Agate)

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Yellow, tan, brownish-green; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (rhombohedral); Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Yellow, tan, brownish-green
Luster: Vitreous to waxy

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Yellow, tan, brownish-green; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (rhombohedral); Specific Gravity: 2.58-2.64.

Formation & geological history

Formed primarily in volcanic and metamorphic rocks as a result of groundwater circulating through cavities (vesicles) or cracks, depositing microcrystalline silica over millions of years. This piece appears to have been water-worn or tumbled.

Uses & applications

Used extensively in lapidary arts, jewelry (cabochons, beads), decorative carvings, and as a popular specimen for collectors due to its durability and unique patterns.

Geological facts

Moss agates are not technically organic moss; their name comes from the dendritic inclusions of manganese or iron oxides that resemble botanical patterns. Agate has been used for over 3,000 years, notably by ancient Egyptians.

Field identification & locations

Identified by its translucency (when held to light), waxy luster, and lack of distinct cleavage. Often found in riverbeds, lake shores (like Lake Superior), and volcanic regions globally.