• A variety of minerals are found in the crust that are commonly found in rocks.

• What are minerals?

• Minerals - natural substances with a fixed chemical composition.

• Minerals exist in the form of: -

1. Elements (Gold, Silver, Mercury, Platinum, Carbon and Sulfur)

2. Compounds (Bauxite, Hematite, , Galena, Cassiterite, Pyrite, Magnesite & Calcite)

Physical & Chemical Characteristics of Minerals

Physical Properties - Hardness and mineral colour

1. Colour

   • Hematite - Reddish-black

   • Malachite - Green

   • Calcite / Limestone - White

   • Galena - Gray

   • Cassiterite - Black

2. Hardness

1. • Sclerometer (a tool to measure mineral hardness)

   • The Mohs Scale determines mineral hardness

   • Calcite (scale 3), Diamond (Scale 10- hardest)

Chemical properties - Solubility in water, mineral heating effect, reaction with acids & alkali.

1. Soluble in water

   • Minerals containing sodium & potassium only dissolve in water

2. The effect of heating

   • Minerals that contain metal oxides are usually not dissolved when heated. However, if heated with carbon, pure metal and carbon dioxide gas will be produced.

   • Minerals containing carbonate and sulfide metals are dissolved when heated.

   • Example:

     • Calcium carbonate -> Calcium oxide + carbon dioxide

     • Zinc sulphide -> Zinc oxide + sulphur dioxide

3. Metals reacts with acid

   • Minerals containing metal oxides and carbonates dissolve in acid and release carbon dioxide gas.

     • Calcium carbonate + hydrochloric acid --> calcium chloride + carbon dioxide + water 

Uses of Minerals

• Calcium oxide and calcium carbonate - neutralize acidic soils.

• Calcium carbonate - used in gas furnaces to remove impurities during iron extraction.

• Silicone dioxide - make glass.

• Aluminum oxide - a substance in sunscreen, lipstick & nail polish.

Reactivity Series of Metals Based on Reactions with other metals

• The position of a metal in the reactivity series of metals depends on the reactivity of the metal when reacting with oxygen.

• More reactive metals will remove oxygen from less reactive metal oxide when both metals react.

• Zinc is more reactive than copper. When the mixture of zinc and copper oxide is heated, zinc will remove oxygen from the copper oxide, while zinc will become zinc oxide

  • Zinc + Copper oxide --> Zinc oxide + Copper

• Magnesium is more reactive than zinc. When the mixture of zinc and magnesium oxide is heated, there no reaction occur.

  • Zinc + Magnesium oxide --> no reaction occur

Position of Carbon & Hydrogen in the Reactivity Series of Metals

• Metals which are less reactive than carbon in the reactivity series of metals can be extracted from their ores through the reduction of the oxide of these metals by carbon. 

• Examples

  • Zinc oxide + Carbon --> Zinc + Carbon dioxide

  • Lead (II) oxide + Carbon --> Lead + Carbon dioxide

• The metal that more reactive than carbon in it metal reactivity series cannot be extracted from their ores.

• Example

  • Aluminium oxide + Carbon --> no change

• Application of the position of carbon in the reactivity series of metals for industrial use is metal extraction. 

• Metals which are less reactive than hydrogen in the reactivity series of metals can be extracted from their ores through the reduction of the oxide of these metals by hydrogen. 

• Examples

  •  Iron (III) oxide + Hydrogen -->  Iron + water

  • Lead (II) oxide + Hydrogen --> Lead  + water

• The metal that more reactive than hydrogen in it metal reactivity series cannot be extracted from their ores.

• Example

  • Aluminium oxide + Hydrogen --> no change

• Hydrogen cannot reduces aluminium oxide

• Extraction of metals is the process to obtain metals from their ores.

• For metals higher than carbon in the reactivity series of metals, the extraction of the metal from its metallic compound is through electrolysis. 

  • Potassium, sodium, calcium, magnesium and aluminium

• For metals lower than carbon in the reactivity series of metals, the extraction of the metal from its ore is through the reduction of its oxide with carbon. 

  • Zinc, iron, tin and lead 

• Extraction of the copper and mercury metals is done through direct heating of the metallic compounds. 

Process of Iron Extraction 

• The extraction of iron from its ore is carried out in a blast furnace.

1. A mixture of concentrated iron ore or iron oxide, coke and limestone is added into a blast furnace through the top 

2. A very hot blast of air is pumped into the furnace through the bottom. 

3. Reactions that occur in the furnace at high temperature. 

   • Production of iron 

     1. Iron(III) oxide + carbon -->iron + carbon dioxide 

     2. Iron(III) oxide + carbon monoxide--> iron + carbon dioxide 

     3. Iron(II) oxide + carbon--> iron + carbon dioxide 

   • Production of slag 

     1. Calcium carbonate -->calcium oxide + carbon dioxide 

     2. Calcium oxide + silicon dioxide -->calcium silicate 

At high temperature in the furnace, 

1. iron that is produced will melt. The molten iron that has solidified is known as cast iron.

2. slag that is produced will melt. From time to time, the molten slag is tapped off and used to make the base of buildings and roads.