Watch the Open Am Tuning online guitar lesson by Sonny Landreth from Slide Supernatural
A minor tuning is the same as A major tuning except dropping down on the second string from C# to C natural. Spelling low to high - go back down to the big E. Go to the fifth string we have the A. Go on up to the fourth string we have an E octave. Up to the third string, another A. Then up to the second string we drop down to the C natural. So when you finish up with the top and get the E there you have an A minor chord. It's real shimmery. Because of the tension, you have a lot of that going on with the harmonics, this tension brings that out more, and I think that effect on the upper partials is really hip. And it's worth mentioning that both G minor and A minor would be in the same position, so you don't have to change in learning those particular notes, which is helpful.