gemstone

White Agate / Chalcedony

Silicon Dioxide (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, milky white to translucent color, waxy to vitreous luster, microcrystalline (cryptocrystalline) quartz structure, conchoidal fracture with no true cleavage, specific gravity of 2.60 to 2.65.

Identified July 31, 2026More gemstone →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater, typically in cavities of igneous and sedimentary rocks. Over millions of years, silica-rich solutions precipitate microcrystalline quartz layers.

Uses & applications

Commonly used for making tumbled stones, beads, cabochons for jewelry, carvings, and decorative ornamental items.

Geological facts

Agate has been used since ancient times (dating back to the Neolithic period) for amulets, seals, and ornamental vessels due to its durability and pleasing appearance when polished.

Field identification & locations

Can be identified in the field by its smooth, water-worn texture when found in riverbeds, waxy feel, hardness that scratches glass, and microcrystalline structure. Found worldwide, particularly in regions with volcanic activity.