If you've got a chrome metal-shelled drum with a Zoomatic, it's almost certain to be brass. If it has three fine lines circling the drum, that's another indicator of a brass shell.

Slingerland did make an aluminum drum, but it would be obvious if that's what you had. They weren't chromed and had a bare metal finish, so there's no mistaking them. Many of them had a horizontal ribbed appearance like the one in the attached pic.

I just happen to have a brass 5" x 14" Slingy shell laying around (1975-ish) and I weighed it so you can compare: 1464g or about 3 lbs., 4 oz.

If you have a student model aluminum drum it does not have a zoomatic strainer on it it has a rapid strainer, here is a pic of one I own this is a ten lug model they also come in eight lug models to! also they are not chromed but aluminum.

HOW COOL! I just picked up the exact snare drum at a flea market last week (it's an 8-lug though).I tuned it up ,doesnt sound too bad,because of my love for the Ludwig sound,this drums probably gonna end up being a 'space invader' in my collection(Did,nt someone inquire about this exact drum in Modern Dummer a few months back?)