CoachA natural material is used much as it is found in nature, only cut or shaped: wood, stone, cotton, wool, leather. A manufactured material is made by people from substances found in nature, by changing them, often with heat and chemical changes: glass, steel, aluminium, plastic, paper, concrete.
Examples
Example 7.2 (Two tables)
A table made of oak planks is made of a natural material: the wood was only sawn, planed and glued. A table with a glass top and steel legs is made of manufactured materials: neither glass nor steel is found as such in nature.