Fabric content is unknown; I would absolutely say this is a cotton pique
The lining looks like cotton.
The back looks like a separate piece (but it is attached) and comes around the front to buckle at the waist.
The skirt is pleated at the waist on either side. The buckle is a nifty rhinestone design and all the stones appear to be intact.
Back lapped metal zipper
This dress is FABULOUS! I could see this going to The Kentucky Derby, or any other horse racing event. A summer wedding. A barbecue. Maybe not a barbecue.