Laterite Nickel Deposits in Geology

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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?

Olivine, pyroxene, and serpentine Signup and view all the answers

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

Neogenesis of magnesium hydrosilicates Signup and view all the answers

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

New Caledonia Signup and view all the answers

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

Manganese Signup and view all the answers

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

Their collapse breccias structure Signup and view all the answers

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

Through mineralogical and geochemical investigations 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?

Chrysocolla and malachite Signup and view all the answers

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

Because they are enriched in manganese and gold Signup and view all the answers

What type of deposit are gossans mainly considered to be?

Bauxite ore deposits Signup and view all the answers

What process causes alumina enrichment in aluminium silicate rocks?

Leaching of SiO2 and iron Signup and view all the answers

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

35% Signup and view all the answers

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

Karst bauxite Signup and view all the answers

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

Australia Signup and view all the answers

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

Reduced cost in exploration and processing Signup and view all the answers

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

Low deposit size and iron grades Signup and view all the answers