mineral

Weathered agate or chalcedony nodule

Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; milky gray-blue translucent areas contrast with a brown, iron-stained rough surface. Quartz has a trigonal structure, though its microscopic crystals are too fine to see; no obvious cleavage and a waxy to vitreous luster.

Identified October 3, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited chalcedony in a cavity or fracture, later exposed by weathering; the specimen’s age and precise formation setting cannot be determined from the image.

Uses & applications

Agate and chalcedony are used for beads, cabochons, carvings, and ornaments; rough pieces are collected. This small irregular fragment appears mainly suited to collecting.

Geological facts

Agate is banded chalcedony, but banding is not clearly visible here, so the identification is provisional.

Field identification & locations

Look for waxy luster, translucent edges, and hardness sufficient to scratch glass; brown coloration commonly comes from iron oxides. Chalcedony occurs worldwide, including volcanic cavities and sedimentary deposits.