mineral

Tumbled Gray Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Translucent gray to brownish-gray; Luster: Vitreous to waxy (when polished); Crystal structure: Hexagonal (cryptocrystalline); Cleavage: None; Fracture: Conchoidal.

Hardness: 6
Color: Translucent gray to brownish-gray
Luster: Vitreous to waxy (when polished)

Identified July 14, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Translucent gray to brownish-gray; Luster: Vitreous to waxy (when polished); Crystal structure: Hexagonal (cryptocrystalline); Cleavage: None; Fracture: Conchoidal.

Formation & geological history

Agates form primarily in volcanic and metamorphic rocks. This specimen formed as silica-rich groundwater deposited microscopic quartz crystals in cavities of lava or other rock types over millions of years.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative objects, metaphysical healing practices, and as a collector's item for beginners.

Geological facts

Agate is a variety of chalcedony. While this specimen is a plain gray, many agates feature vibrant bands. Polishing these stones in a rock tumbler enhances their waxy luster and reveals internal patterns.

Field identification & locations

Identify by its waxy texture, hardness (it will scratch glass), and translucency when held to a light source. Commonly found globally in areas with volcanic activity like Brazil, India, and the USA.