sedimentary
Hematite or Goethite-rich Ironstone
Ironstone (Oxidized Iron Ore)
Hardness: 5-6 (variable), Color: Reddish-brown, dull to earthy luster, non-crystalline to massive structure, specific gravity high (approx 4.0-5.3)
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Physical properties
Hardness: 5-6 (variable), Color: Reddish-brown, dull to earthy luster, non-crystalline to massive structure, specific gravity high (approx 4.0-5.3)
Formation & geological history
Formed through the chemical precipitation of iron-rich minerals in aqueous environments or the intense weathering/leaching of iron-bearing rocks (lateritization).
Uses & applications
Primary source for iron ore extraction, pigment for paints (ochre), and in construction as a sturdy aggregate.
Geological facts
Ironstone was the backbone of many early industrial revolutions; the red planet Mars gets its signature color from iron oxides similar to those in this specimen.
Field identification & locations
Identify in the field by its significant weight (density), reddish-brown streak on a porcelain plate, and lack of magnetism (unlike magnetite). Found globally in sedimentary basins.
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