Step 1: Match zircon.
Zircon stands out under the microscope with very high positive relief, so it looks like it sits proud of the slide. So P, zircon, takes (ii).
Step 2: Match orthopyroxene.
Orthopyroxene shows soft pink to green pleochroism, changing colour as the stage turns. So Q, orthopyroxene, takes (i).
Step 3: Match muscovite.
Muscovite is a mica with low relief, and the cyclic twinning feature pairs with it here. So R, muscovite, takes (iii).
Step 4: Match cordierite.
Cordierite is left with the third order birefringence feature, which is the remaining choice. So S, cordierite, takes (iv).
Step 5: Put it together.
The full match is P-ii, Q-i, R-iii, S-iv.
\[ \boxed{\text{P-ii; Q-i; R-iii; S-iv}} \]
