Question 6 of 9intermediate💡 UnderstandShort Answer3 marks

How are minerals formed in igneous and metamorphic rocks?

Correct Answer

In igneous and metamorphic rocks, minerals occur in cracks, crevices, faults or joints. The smaller occurrences are called veins and the larger ones are called lodes.

These minerals are formed when minerals in liquid/molten and gaseous forms are forced upward through cavities towards the earth's surface. As they rise, they cool and solidify in these cracks and joints.

Major metallic minerals like tin, copper, zinc and lead are obtained from such veins and lodes.

Exercise: EXERCISES | Q: 2(iii) | (Page Page 15)
For More Understanding

Explanation

The textbook clearly explains the mode of occurrence of minerals in igneous and metamorphic rocks under point (i). The answer covers three key aspects: (1) location - cracks, crevices, faults or joints; (2) terminology - veins (smaller) and lodes (larger); and (3) formation process - upward movement of molten/gaseous minerals through cavities, followed by cooling and solidification. The examples of metallic minerals (tin, copper, zinc, lead) add completeness to the answer.

Solution Steps

  1. Step 1: Identify where minerals occur in igneous and metamorphic rocks (cracks, crevices, faults, joints)

  2. Step 2: Explain the terminology - veins (smaller) and lodes (larger occurrences)

  3. Step 3: Describe the formation process - upward movement of molten/gaseous minerals through cavities, cooling and solidifying as they rise

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