LAND AND ITS RESOUCES

    MINERALS FOUND IN THE EARTH'S CRUST
1. Minerals are natural element or compound present in the Earth's crust.
2. minerals exist as natural element include
    a)  gold
    b)  silver
    c)  platinum
    d) antimony
    e) arsenic
     f)  iron (from meteorites)
    g)  copper
    h)  mercury (can be found in thermometer)
3. these free element are found in nature because they are inactive and does not combine with other elements.
4. minerals which exist as naturals compound include the examples given below
 

MINERALS	MAIN COMPOUND	CONSTITUENT ELEMENT
Haematite	Iron Oxide	Iron & Oxygen
Galena	Lead Sulphide	Lead & Sulphur
Calcite	Calcium Carbonate	Calcium, Carbon & Oxygen
Cassiterite	Tin Oxide	Tin & Oxygen
Malachite	Copper Carbonate	Copper, Carbon & Oxygen
Iron Pyrite	Iron Sulphide	Iron & Sulphur
Silica	Silicon Dioxide	Silicon & Oxygen

• PHYSICAL PROPERTIES OF MINERALS

1. mohs' scale is a useful test for hardness of minerals.
2. for each number of hardness in the scale one minerals is used as a standard.

       Table below show the hardness of minerals.

       

3. all minerals found in the earth's crust are not soluble in water. they have remained in the earth's crust for              more than 2000 million years