1. Examine a flake of Muscovite and look at the interference figure it provides, notice the fringes on the isogyres. To what crystal system could it belong, how can you tell? (just infer, the figures on these microscopes are probably not good enough for accurate dispersion work).

2. Examine a grain of Titanaugite (1,2) (BH53 [7] or ask your TA to find one for you). Titanoaugite shows strong dispersion of the optic axes r >> v. Note that the grain never entirely goes extinct.