sedimentary

Ironstone Nodule

Ironstone (Ferruginous Rock)

Hardness: 5-5.5 (variable); Color: Dark grey, rusty brown, or reddish-brown; Luster: Dull, earthy to sub-metallic; Cleavage: None; Structure: Massive or concretionary; Specific Gravity: 3.0-3.8.

Hardness: 5-5
Color: Dark grey, rusty brown, or reddish-brown
Luster: Dull, earthy to sub-metallic

Identified July 13, 2026More sedimentary →

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Physical properties

Hardness: 5-5.5 (variable); Color: Dark grey, rusty brown, or reddish-brown; Luster: Dull, earthy to sub-metallic; Cleavage: None; Structure: Massive or concretionary; Specific Gravity: 3.0-3.8.

Formation & geological history

Formed through the accumulation of iron minerals (siderite, goethite, hematite) in sedimentary environments, often precipitated from groundwater or deposited in marine and boggy settings over millions of years.

Uses & applications

Historically used as a common iron ore for smelting; currently used for landscaping, as a minor decorative stone, or as educational geological specimens.

Geological facts

These nodules are often mistaken for meteorites because of their dark color, high density, and occasional magnetic properties, earning them the nickname 'meteor wrongs.'

Field identification & locations

Identify by its significant weight compared to common rocks, rusty surface staining, and streak test (usually brown or reddish). Commonly found in stream beds or eroded soil layers.