minerals

6.0 LAND AND ITS RESOURCES6.1 Analysing the various minerals found in the Earth’s crust.

Prepared by:

L.C. Seah

Learning Outcomes:

• describe what a mineral is, • explain through examples that

minerals exist in the form of natural elements or natural compounds,

• identify the elements in natural compounds,

• describe the properties of minerals,

• write equations in words to show the effect of heat on the minerals.

Minerals

Element Compound

Metal Non-metalSilicon

compoundCalcium

carbonate

Minerals• Hard• Do not dissolve in water

Element

• Platinum• Carbon• Mercury

• Sulphur• Silver• Gold

Compound

• Carbonate• Oxide• Silicate• Sulphide

Natural mineral content

• Bauxite – Aluminium oxide• Cassiterite – Tin oxide• Hematite – Iron oxide• Magnesite – Magnesium carbonate• Malachite – Copper carbonate• Galena – Lead sulphide• Limestone/Marble – Calcium

carbonate

Properties of minerals

• Hardness• Solubility in water• Effect of heat

Colours

• Hematite – Brown• Malachite – Green• Bauxite – White• Cassiterite – Black• Galena – Grey• Iron pyrite – Black• Limestone - White

Physical

• Hard minerals

Chemical characteristics

• Do not dissolve in water• Metal oxide and silicate do

not decompose when heated

• Metal carbonates and sulphides can be easily decomposed by heating

Effect of heat on metal carbonate

Metal carbonate

metal oxide + carbon dioxideheated

Zinc carbonate

zinc oxide + carbon dioxideheated

Test by lime water

Effect of heat on metal sulphide

Metal sulphide

heated

Test by

oxygenMetal oxide +

Sulphur dioxide+

Magnesium sulphide

heatedoxygen

Magnesium oxide +

Sulphur dioxide+

acidic potassium manganate (VII) solutionacidic potassium dichromate (VI) solution

Test yourself:

1 Name the elements or chemical compounds that are naturally present in the Earth’s crust.

2 State four examples of natural elements that exist freely in the Earth’s crust.

3 State four examples of minerals that exist in the form of compounds in the Earth’s crust.

Test yourself:

4 State two common properties of most of the minerals in the Earth’s crust.

5 Write an equation in word form to represent the reaction between magnesium sulphide and oxygen.

Answer:

1 Mineral2 Gold, silver, platinum and mercury3 Oxide, carbonate, sulphide and

silicate4 Hard and do not dissolve in water5 Magnesium sulphide + oxygen →

magnesium oxide + sulphur dioxide