sedimentary

Likely weathered chert or siliceous limestone fragment

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃)

AI-generated identification · may be incorrect

Small angular gray-brown fragment with a pale, weathered surface and darker granular interior; likely dull to weakly waxy luster. Chert has hardness ~7 and no cleavage; limestone is softer, ~3, and fizzes with dilute hydrochloric acid.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Most plausibly a weathered sedimentary fragment from Cretaceous–Paleozoic rocks common in the Ark-La-Tex region, formed by silica replacement of carbonate sediment or by lithified carbonate mud. Exact identification requires tests.

Uses & applications

Chert is used historically for sharp tools and occasionally aggregate; limestone is widely used for cement, lime, aggregate, and building stone. This small piece has negligible commercial value.

Geological facts

The image cannot reliably distinguish chert from limestone or a siliceous breccia. A glassy fracture and lack of acid reaction favor chert; vigorous fizzing favors limestone.

Field identification & locations

Near 33.5°N, 94.0°W, sedimentary chert, novaculite-like silica, and limestone fragments are regionally plausible. Test an inconspicuous spot with vinegar or dilute HCl, and check whether it scratches glass; avoid confusing a scratch with surface abrasion.