sedimentary

Beach sandstone or cemented beachrock fragment

Lithified carbonate- or silica-rich sand; commonly calcarenite or quartz sandstone

AI-generated identification · may be incorrect

Brown, porous, and coarse-grained with sand-sized particles in a cement matrix; typically Mohs 2–7 depending on calcite versus quartz cement, dull to earthy luster, and no obvious cleavage. The strongly curved shape may reflect erosion around a cavity or cemented beach debris.

Identified August 26, 2026More sedimentary →

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At a glance

Common name: Beach sandstone or cemented beachrock fragment
Scientific name: Lithified carbonate- or silica-rich sand; commonly calcarenite or quartz sandstone
Category: sedimentary
Identified: August 26, 2026
Method: Standard

AI Estimated Value

Usually $0–$10 as a beach specimen; up to about $10–$30 if unusually shaped, demonstrably local, or presented as a geological teaching specimen.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Likely formed when beach sand was cemented by calcite, aragonite, or iron oxides in the intertidal zone, producing beachrock; age is probably Holocene, though exact age cannot be determined visually. Wave abrasion and weathering shaped the specimen.

Uses & applications

Used locally as construction stone or aggregate, but this irregular fragment has mainly educational or decorative value. It is not generally suitable for jewelry.

Geological facts

The dark brown color may come from iron-oxide staining or organic material, while the holes likely represent weathered grains, shell fragments, or former cavities. A drop of dilute hydrochloric acid that fizzes suggests carbonate cement.

Field identification & locations

Common on tropical and subtropical shorelines and around uplifted or cemented beaches. Examine fresh surfaces for visible quartz grains or shell fragments; avoid assuming it is pumice, because it lacks pumice’s glassy texture and extreme lightness.