HOLLOW IRONSTONE CONCRETION - Suffolk
« backHOLLOW IRONSTONE CONCRETION
Red Crag
Bawdsey, Suffolk
In unconsolidated sedimentary rocks iron is often dissolved in the groundwater and can be redeposited as hard, insoluble layers of iron oxide. Round or odd-shaped concretions are sometimes formed consisting of concentric layers of iron minerals such as limonite and goethite.
In this case the concretion consists of a hard limonite 'shell'. It appears that the iron compounds slowly migrated outwards from a central point, until crystallising as a limonite layer.
This is a very good example. A geological curiosity!
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Size: 8.5 x 7.5 x 3.5 centimetres
Weight: 144 grams