(a) Describe four characteristics of igneous rocks
(b) Using specific examples, state four ways in which metamorphic rocks are useful to man.
Explanation
(a) Solution (a) Igneous rocks
(1) Formed from cooled and solidified magma
(2) Hardened rocks
(3) Can be formed beneath the earth as intrusive rocks. Examples are gabbro, granite, etc.
(4) Or on the surface of the earth as extrusive rocks
(5) Contain crystals
(6) Are either acidic or basic
(7) Vary in colour (light or dark)
(8) Crystal’s size varies from specks to glassy mass
(9) Non-stratified
(10) Do not contain fossils.
(b) Importance of metamorphic rocks
(1) Marble for floor tiles
(2) Graphite for lead pencils
(3) Gneiss for construction purposes
(4) Slate, and marbles are minerals/raw materials for industries
(5) Kaolin for ceramic products
(6) Foreign exchange earnings e.g. from graphite, marble, etc
(7) Emeralds for jewelry