sedimentary

Rounded iron-rich pebble

Likely ferruginous sandstone or ironstone; exact identification is uncertain from the photograph

AI-generated identification · may be incorrect

Brown to ochre, dull earthy luster, fine-grained and rounded, with possible iron-oxide staining; hardness likely about 5–7 Mohs. No visible crystals or cleavage are apparent.

Identified September 12, 2026More sedimentary →

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Physical properties

Brown to ochre, dull earthy luster, fine-grained and rounded, with possible iron-oxide staining; hardness likely about 5–7 Mohs. No visible crystals or cleavage are apparent.

Formation & geological history

Probably a naturally weathered and transported sedimentary fragment, cemented or stained by hematite/goethite; its geological age cannot be determined visually. Such pebbles form in river, beach, or glacial gravels.

Uses & applications

Common pieces have little industrial or jewelry use, though ironstone may be crushed as aggregate or iron ore when sufficiently iron-rich. This specimen has mainly educational or casual collecting value.

Geological facts

The rusty coloration commonly comes from hematite (Fe₂O₃) and/or goethite (FeO(OH)); a streak test can distinguish them from many ordinary brown rocks.

Field identification & locations

Look for a reddish-brown streak on unglazed porcelain, strong weight, and possible attraction to a magnet; fizzing with dilute acid would suggest carbonate cement instead. Common worldwide in gravel deposits.