Section A
Q1. Write down the symmetry elements required for different crystallographic systems. Corresponding to each system, give suitable examples of minerals.
(a) Write down the symmetry elements required for different crystallographic systems. Corresponding to each system, give suitable examples of minerals.
(b) For mafic igneous rocks, draw labelled sketches for corona structure and porphyritic texture. Comment briefly on their petrogenetic significance.
(c) What do you mean by birefringence and twinning in minerals? Give some common examples of twinning found in quartz.
(d) Write briefly on retrograde metamorphism.
(e) What are turbidites? Give the sequence of bed-forms produced by turbidity currents.