Chapter 6.8 | Weathering & Ore Deposits

Secondary Enrichment

weathering concentrates metals into economically valuable concentrations

In what 2 ways does secondary enrichment occur?

chemical weathering leaves behind desired elements, or removes desired elements & carries to lower zones

What happens where chemical weathering removes undesired materials?

desired materials concentrated in upper zones of soil

What happens when chemical weathering removes desired materials?

desired materials concentrated in lower zones of soil

Bauxite

principal ore of aluminum

How is bauxite formed?

rainy tropical climates, ions in al-rich rocks weather away & leave aluminum behind

Why does aluminum concentrate in bauxite during chemical weatherings?

extremely insoluble

What does the presence of bauxite indicate?

previous wet tropical climate

What other mineral ores form like bauxite?

nickel & cobalt

What are the environmental concerns of mining bauxite?

mining removes vegetation, soil dries out, rain forest destroyed

How do copper and silver deposits form?

weathering concentrates metals in low-grade primary ore, often includes pyrite

Why is pyrite important in deposits?

chemical weathering forms sulfuric acid, allows water to dissolve ore metals

Why does deposition of metals like copper and silver occur?

changes in chemistry of solution carrying the ions

What is bauxite an example of? Compare that to copper and silver deposits:

bauxite is chem weathering leaving desired mineral behind, copper & silver are chem weathering moving mineral into concentrated area