mineral

Agate

Chalcendony (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale; Color: White, grey, and waxy translucence with dark inclusions; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: White, grey, and waxy translucence with dark inclusions
Luster: Waxy to vitreous

Identified June 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral in cavities (vesicles) of volcanic rocks (basalt/andesite) or sedimentary rocks through the deposition of silica from groundwater. Often millions of years old.

Uses & applications

Used primarily for jewelry (cabochons, beads), decorative ornaments, and historically for precision instruments like mortars and pestles due to hardness.

Geological facts

Agate is a variety of chalcedony characterized by its translucency and fine grain. This specific specimen appears to be a tumbled or water-worn river agate with dendritic or 'moss' style inclusions.

Field identification & locations

Identify in the field by its waxy appearance, conchoidal fracture (curved breaks), and translucency when held to light. Found globally in volcanic areas and riverbeds.