I clearcut a stand of spearmint and turned it into three jars of what should become mint extract:
The left jar has 3 ounces of mint mostly covered with 80 proof vodka and the other two jars each have 5 ounces submerged in 180 proof grain alcohol.
Nine days later:
The vodka is now on the right and shows a weird layering caused by the leaves extending above the light yellow liquid; I’ve been inverting the jars every few days. The grain alcohol looks more like the previous iteration, with uniformly decolored leaves in dark green liquid.
A closer look:
What’s happening in the vodka jar does not look like a nominal outcome …
The Smell of Molten Projects in the Morning 
Certainly interesting. Maybe a chemist can comment? Or at least someone who had more chemistry than I did.
I can’t imagine anything normally feeding on mint leaves that could survive in vodka, but imagination has never been my strong suit.
Plan: unscrew the lid outdoors at arm’s length.