Laterite Nickel Deposits in Geology
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Questions and Answers

How do lateritic nickel ore deposits form?

  • From intensive and long-lived tropical weathering of ultramafic rocks (correct)
  • From hydrothermal activity
  • From volcanic eruption
  • From metamorphic rocks
  • What are the two types of nickel laterite distinguished based on?

  • Nickel content in the upper part
  • Presence of olivine in the rock
  • Location within the regolith (correct)
  • Color of the soil
  • How does meteoric water contribute to the formation of lateritic nickel ore deposits?

  • By causing oxidation of iron minerals
  • By creating acidic rain that dissolves nickel
  • By direct precipitation of nickel minerals
  • By percolating through the soil and redistributing nickel (correct)
  • What minerals are rapidly decomposed by acidic rain and soil water in the formation of lateritic nickel ore deposits?

    <p>Olivine, pyroxene, and serpentine</p> Signup and view all the answers

    Which process results in the immobilization of nickel by ion exchange in lateritic nickel ore deposits?

    <p>Neogenesis of magnesium hydrosilicates</p> Signup and view all the answers

    Which region is identified as the largest ore province of Ni-laterites?

    <p>New Caledonia</p> Signup and view all the answers

    Which mineral is most commonly associated with iron hydroxides in gossans?

    <p>Manganese</p> Signup and view all the answers

    What is a characteristic feature of gossans that makes them prominent indicators for hidden sulphide ore?

    <p>Their collapse breccias structure</p> Signup and view all the answers

    How can geologists distinguish between valuable ore gossans and 'false gossans'?

    <p>Through mineralogical and geochemical investigations</p> Signup and view all the answers

    In the secondary zonation of a deeply weathered copper sulphide ore deposit, what minerals are typically found below the groundwater table?

    <p>Chrysocolla and malachite</p> Signup and view all the answers

    What is one of the main reasons gossans are considered prime prospecting guides?

    <p>Because they are enriched in manganese and gold</p> Signup and view all the answers

    What type of deposit are gossans mainly considered to be?

    <p>Bauxite ore deposits</p> Signup and view all the answers

    What process causes alumina enrichment in aluminium silicate rocks?

    <p>Leaching of SiO2 and iron</p> Signup and view all the answers

    What is the minimum percentage of Al2O3 required for bauxite to be economically exploitable?

    <p>35%</p> Signup and view all the answers

    Which type of bauxite is associated with high level or upland areas?

    <p>Karst bauxite</p> Signup and view all the answers

    In which region was the Boddington bauxite mine, one of the largest lateritic gold deposit representatives?

    <p>Australia</p> Signup and view all the answers

    What is the characteristic that makes lateritic gold deposits attractive for mining compared to hard rock deposits?

    <p>Reduced cost in exploration and processing</p> Signup and view all the answers

    What limits the importance of lateritic iron ore deposits as a source of iron?

    <p>Low deposit size and iron grades</p> Signup and view all the answers

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