mineral

Water-worn agate (chalcedony) pebble

Microcrystalline quartz, SiO₂; likely agate/chalcedony

AI-generated identification · may be incorrect

Translucent white-to-tan with rusty-brown patches and a waxy luster; quartz crystal structure, no visible cleavage, Mohs hardness about 6.5–7, specific gravity about 2.6. Its rounded shape and surface suggest natural abrasion, though the image does not show diagnostic banding.

Identified October 11, 2026More mineral →

Explore Water-worn agate (chalcedony) pebble 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

Silica-rich groundwater deposited microscopic quartz in cavities or fractures, later forming chalcedony; iron oxides likely caused the brown staining. Agate occurs in rocks of many ages, commonly volcanic cavities and sedimentary settings.

Uses & applications

Used for jewelry, beads, carvings, and ornamental objects; common pebbles are mainly collected or used decoratively.

Geological facts

Agate is a variety of chalcedony, and its fine quartz crystals are too small to distinguish without magnification.

Field identification & locations

Look for hardness, waxy translucence, and—where present—distinct curved bands; brown coloration may be iron staining. Agates occur worldwide, including Brazil, Uruguay, India, and the western United States.