sedimentary
Ironstone Pebble
Sedimentary Ironstone (Hematite/Limonite-bearing)
Hardness: 5.5-6.5 on Mohs scale; Color: reddish-brown, rusty orange, brownish-tan; Luster: dull to earthy; Crystal structure: microcrystalline to massive; Cleavage: none.
- Hardness
- 5
- Color
- reddish-brown, rusty orange, brownish-tan
- Luster
- dull to earthy
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Physical properties
Hardness: 5.5-6.5 on Mohs scale; Color: reddish-brown, rusty orange, brownish-tan; Luster: dull to earthy; Crystal structure: microcrystalline to massive; Cleavage: none.
Formation & geological history
Formed by the precipitation of iron oxides (such as hematite, limonite, or goethite) within sedimentary layers, often rounded into smooth pebbles by water action in riverbeds or coastal environments.
Uses & applications
Historically used as an ore of iron; small pebbles are commonly used in landscaping, gravel mixes, or as educational specimens for identifying sedimentary iron minerals.
Geological facts
Ironstone gets its distinctive reddish-brown color from weathered iron minerals. It often forms concretions that resist erosion better than surrounding soft rocks.
Field identification & locations
Identified by its heavy feel relative to size, rusty streak, and dull reddish-brown surface. Commonly found along riverbeds, gravel walkways, and in sedimentary rock formations worldwide.
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