Minerals in the Earth’s Crust

oxygensiliconaluminiumironcalciumsodium

Elements in the Earth’s crust

GoldSilverPlatinum

Natural elements

Natural compounds- oxides

Haematite – iron oxide

Cassiterite – tin oxide

Natural compounds - carbonate

Calcite – calcium carbonate

Malachite –copper carbonate

Natural compounds - sulphides

Iron pyrite –Iron sulphide

Galena –Lead sulphide

1. Hardness of minerals2. Solubility of minerals in water3. Action of heat on minerals

Properties of minerals

Can be measured using Mohs’ scale

The hardest is diamond (10)The softest is talc (1)

Hardness of minerals

Most minerals are insoluble in water

Only oxides, sulphates and carbonates of potassium and sodium are soluble in water

Solubility in water

Most metal oxides are stable, do not break down when heated, except less reactive metals.

Mercuric oxide mercury + oxygen

Effect of heat

1. Very hard except oxides of potassium, sodium, calcium and magnesium

2. Donot dissolve in water3. Do not decompose on heating

except mercury oxide

Metal oxides

Break down into metal oxide and sulphur dioxide when heated

Iron sulphide iron oxide + sulphur dioxide

Sulphur dioxide bleaches acidified potassium manganate(VII) solution from purple to colourless

Metal sulphide

Metal carbonate break down into metal oxide and carbon dioxide when heated

Calcium carbonate calcium oxide + carbon dioxide

Metal carbonates