mesceline

I got some synthetic mesceline at bonnaroo last year and am saving it for a time me and a friend can get back together and go camping with it. Just wondering if anyone knows if they keep well or what makes them go bad or what? Its a capsul full of white powder, looks just like any other pill of mesceline I've seen

if it's anything like acid or other psychos., put it in the freezer in an air-tight container.