mineral

White Agate (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Milky white to translucent grey with subtle banding; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Milky white to translucent grey with subtle banding
Luster: Waxy to vitreous

Identified March 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities (vesicles) of igneous volcanic rocks or sedimentary layers. They can range in age from a few million to hundreds of millions of years depending on the host rock formation.

Uses & applications

Used primarily in lapidary arts for jewelry (beads, cabochons), spirit carvings, and as decorative tumbled stones. Industrially used for precision pendulums and mortars and pestles due to its hardness and resistance to acids.

Geological facts

Agate is a variety of chalcedony characterized by its microcrystalline grain. The name 'Agate' comes from the Achates River in Sicily where they were found in ancient times. Unlike quartz crystals, agates are translucent and form in concentric layers.

Field identification & locations

Identify by its waxy luster, translucency when held to light, and lack of visible crystal faces. Common in riverbeds, beaches, and volcanic regions. Handheld specimens like this tumbled piece are often found in 'rock shops' or as beach pebbles.