This is a reddish orange patch on leaves. It is caused by temperature flucuations. The plant will usually come out of it if it is only a small patch of it, but if a large patch appears, cut the plant back. To control mint-move it once in a while to a new location. Or plant it in drain pipes buried in the ground or plant it every year in a above gound planter.
Some people plant low growing mints as a ground cover or lawn.
When drying mint, you will notice some of the flavor is gone. Hang mint in bunches in a brown paper bag until leaves are dry enough to crumble. Fill an airtight jar and it will keep for 1 year. You can freeze mint by placing on a cookie sheet and freeze until solid-then place in a plastic bag and store in freezer for up to one year. Warm 8 oz. of honey and add 1 tablespoon mint leaves.