sedimentary
Ferromanganese Nodule
Polymetallic Nodule (composed primarily of MnO2 and Fe2O3)
Hardness: 1-4 (Mohs scale), Color: Dark brown to black, Luster: Dull/Earthy, Crystal Structure: Amorphous/Cryptocrystalline, Texture: Botryoidal or Mammillated (rough and bumpy), Specific Gravity: 2.1 - 3.5.
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Physical properties
Hardness: 1-4 (Mohs scale), Color: Dark brown to black, Luster: Dull/Earthy, Crystal Structure: Amorphous/Cryptocrystalline, Texture: Botryoidal or Mammillated (rough and bumpy), Specific Gravity: 2.1 - 3.5.
Formation & geological history
Formed by the precipitation of manganese and iron oxides from seawater over millions of years, often around a core such as a shark tooth, pebble, or shell fragment. They are found on the abyssal plains of the deep ocean.
Uses & applications
Potentially a major source of critical metals like cobalt, nickel, copper, and rare earth elements for green technology and batteries; currently a specimen for research and collectors.
Geological facts
These nodules grow incredibly slowly, typically at a rate of only a few millimeters every million years. They are considered one of the slowest geological processes on Earth.
Field identification & locations
Identify by its dark, porous, 'popcorn-like' or bumpy texture and relatively light weight for its appearance. They are most commonly found in deep-sea basins like the Clarion-Clipperton Zone in the Pacific Ocean.
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