sedimentary

Chert or chalcedony pebble (possibly iron-stained)

Microcrystalline quartz, SiO₂; likely chert/chalcedony

AI-generated identification · may be incorrect

Yellow-brown, translucent to opaque, waxy/glassy luster with small conchoidal-looking fractures and possible weathering pits. Quartz hardness is about 7 Mohs; no visible cleavage; specific gravity about 2.6. The white patch may be quartz, calcite, or surface alteration.

Identified September 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica precipitates or replaces sediment, commonly in limestone or gravel deposits; iron oxides produce the ochre color. Exact age cannot be determined visually. Near 30.2°N, 92.3°W, transported chert and silicified gravel are more plausible than locally formed igneous rock.

Uses & applications

Common chert is used for road aggregate, landscaping, and historically cutting tools; attractive translucent pieces may be collected or polished. Typical value is low.

Geological facts

The apparent banding and translucent edges are consistent with chalcedony or agate-like silica, but the photo does not show diagnostic banding clearly.

Field identification & locations

Look for a sharp glassy fracture, hardness sufficient to scratch ordinary glass, and inability to scratch it with a steel knife. Calcite-rich pieces fizz in dilute hydrochloric acid, whereas quartz does not. A streak, hardness, and close inspection of the white material would improve identification.