In a double boiler, melt your soap base. You can also microwave it in 15-second intervals, stirring in between, until melted.
Mix in your coconut oil until combined and add your peppermint essential oil.
Separate the mixture into two separate bowls, adding your mica to one bowl and mix until color is even.
Add ½ cup of sugar to each bowl, one bowl at a time. Mix until well combined. You are looking for a slushy-like consistency.
Pour into your silicone mold. If your mixture gets too thick, heat over the double boiler or microwave on 10-second bursts until you can pour again. Allow the sugar scrub bars to fully dry before removing them from the silicone mold.
Store in an airtight container until ready to use.