mineral

Chalcedony (possibly agate or common quartz)

Microcrystalline quartz, SiO₂

AI-generated identification · may be incorrect

Whitish to pale gray-brown, waxy to dull luster, translucent edges, and irregular conchoidal fracture; hardness about 6.5–7 Mohs, no cleavage, specific gravity about 2.6. The rounded shape appears naturally weathered or lightly worked.

Identified August 8, 2026More mineral →

Explore Chalcedony (possibly agate or common quartz) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, often as a replacement or vein mineral. Chalcedony is generally young relative to its host rock, commonly forming during post-volcanic hydrothermal or groundwater activity.

Uses & applications

Used for carvings, beads, ornaments, lapidary work, and occasionally as an aggregate or decorative stone. Attractive banded varieties are sold as agate.

Geological facts

The specimen resembles massive chalcedony rather than a clearly banded agate; its rough outer rind may be weathering or host-rock residue. The note “kimaha” does not provide a standard mineral identification clue.

Field identification & locations

Common in volcanic regions and sedimentary silica deposits worldwide. Confirm with a scratch test against glass (it should scratch glass), translucent edges, and a conchoidal fracture; avoid damaging valuable pieces.