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MANGANESE NODULES

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First discovered by the HMS Challenger expedition in 1873. Resemble misshapen metallic ... Deep-ocean water lacks significant quantities of manganese or iron ... – PowerPoint PPT presentation

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Title: MANGANESE NODULES


1
MANGANESE NODULES
  • by
  • Mark Sparks

2
Introduction
  • First discovered by the HMS Challenger expedition
    in 1873
  • Resemble misshapen metallic snowballs
  • Found in all the major ocean basins
  • Also known as ferromanganese or polymetallic
    nodules

3
Composition
  • Manganese dioxide average 30 percent by weight
  • Iron oxide average 20 percent by weight
  • Other elements average less than 2 percent by
    weight
  • Fragments serves as a nucleus
  • Nucleus made of carbonates, phosphates, zeolites,
    clays, and silicas

4
Origin
  • Deep-ocean water lacks significant quantities of
    manganese or iron
  • Three possible sources of the manganese and iron
  • Weathering of volcanic material on the ocean
    floor
  • High concentrations of manganese and iron in
    hydrothermal waters at spreading centers
  • Runoff from land
  • Purely chemical or bacterial by-product
  • Bacteria using manganese and iron oxidation in
    their metabolic process theory

5
Occurrences
  • Most commonly found on the ocean floors
  • Can form on lake bottoms
  • Highest concentrations found on vast abyssal
    plains in the deep ocean
  • 4,000 and 6,000 meters
  • Estimated that approximately two billion metric
    tons of manganese nodules lie on the ocean floors
    around the world

6
Growth Rates
  • Extremely slow growth rates
  • Adding 1 mm to 200 mm per million years
  • Correlation between the biological productivity
    of overlying water and the composition and growth
    rates of manganese nodules
  • Biologically unproductive
  • Rich in iron and cobalt
  • Grow at a rate less than 5 mm permillion years
  • Moderate biological productivity
  • High concentrations of nickel, copper, and
    manganese
  • Growth rate 5 mm to 10 mm per million years
  • very productive biological waters
  • Rich in manganese but poor in copper, nickel, and
    cobalt
  • Grow at a rate of 10 mm to 200 mm per million
    years

7
Economical Prospects
  • Caught the attention of mining companies around
    1960
  • Nearly half billion dollars spent researching
    economical value
  • Interest has faded due to a depressed metals
    market

8
Conclusion
  • Exact process of formation is uncertain
  • Result of sediment accumulating around a central
    nucleus
  • Source of the manganese and iron in the ocean
    waters
  • Volcanic activity on the ocean floor
  • Hydrothermal waters at spreading centers
  • Runoff that carries minerals as soluble compounds
    from land
  • Found in all oceans around the world
  • Extremely slow growth rates
  • lt 200 mm per million years
  • Economical value in the metals
  • Cost of extracting from deep ocean basins far
    outweigh the current rate on the metals market

9
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